Please suggest why are they good in terms of being more open source?

It seems to be Freescale/NXP M*Core, is not it?

Please explain how X86 is more open source than ARM?

ARM is almost a pure hardware RISC processor executing supplied instructions directly on its hardware at once.

But X86 is a virtual machine like a Bochs X86 VM generally run on a very high performance hardware RISC processor for which we do not have any documentation at all, look at VIA C3 as an example,

Intel and AMD are the same idea but significantly more optimized for high performance.

Everything is TOP secret about X86 CPUs actual hardware internals, its hardware implementation, its native RISC like assembly instructions, implementation of X86 virtual machine and backdoors injected into this VM yet on the factory and even BIOS initialization procedure at the very beginning of the boot time has so little documentation that only a few boards have unofficial Libreboot firmware for them from hackers who somehow reversed BIOS fragments and/or schematics and initialization sequences.

A few more boards have been made compatible with Coreboot and the most of them are too old and most likely some docs just leaked from laboratories to help coreboot developers to reverse engineer the boards boot process (initialization of RAM modules, etc.).

And ARM initialization process is almost completely open source for some boards, though a few code is still unknown too which is executed before uboot just after getting a reset signal. Can it include some trojan running in a TrustZone isolated and undetectable from OS, may be, who knows.

Uboot needs to be customized for each board, but a few boards have it open source even officially.
For a few boards like AllWinner A20 we have all software parts open source: Uboot unlike proprietary BIOS or UEFI for X86 and even mainline Linux kernel like for X86, even open source 3D driver is being under development and already works.

X86 looks very versatile, has outstanding performance, compatibility with huge amount of add on parts, with fully open source OSes like Linux and BSD supported forever, tens of years after hardware release, it  still can run the most recent modern up to date OSes like BSD. For example the most up to date BSD 2019 at least in text mode still runs fine on 20 years old Pentium 1/2 1997 and even X works well enough if the board has enough RAM like 200-300 Mbytes.

X86 completely hides its initialization code and most likely virtualization spying invisible trojans in negative and/or zero rings of CPU booted before any OS code and fully undetectable from OS level.

Are there any affordable RISC-V boards running Linux and/or BSD on the public market?

Not micro controller boards with some specific non universal OS.

I would not blindly trust neither Russia Today nor any big and significant western mass media.

All of them on the very top are controlled by ZOG and used to manipulate people for a profit of ZOG. They artificially pump up a difference of potentials (like a voltage) in people minds to make more people's debts as a goal to extract more labor from people. ZOG issue (electronically "print") as much money by themselves as they need, but they do not have unlimited labor force, that is why they need a people debt and also for a control.

In Russia this information is actively banned and deleted almost instantly on most forums.
Therefore I conclude they are even afraid of people know about their lie. When I wrote about this on different russian forums they artificially and remotely (I guess by some type of a radio channel may be from satellite, GSM or WIFI) produced a pain in bone marrow of my mother and she called me to get some analgesic for her, I have all (several) calls recordings corresponding by their time to posting on russian forums threads saved to web archive (now deleted from forums).

Also russian people often experience from suffering their human rights (augmented by attackers lie, criminal pressure even from government institutions may be occupied by ZOG agents too) , Russia is not a good place to get truthful official information from, their official big news channels are targeted to get gains and profits only for their government and oligarchs without usual respect to the rest of general people. Mass media generally produce a mixture of truth and false hardly to distinguish from each other just for a manipulation of audience minds, all of them finally lie for ZOG profit.

It is a Heads distro installation.

Fixed by manually (dpkg -i *deb) upgrading  to versions from a newly bootstrapped directory.

Well, I have installed Devuan Ascii from scratch into KVM VM and was able to run it with external kernel supplied as a qemu parameter.

Though I did not try 9P root anymore because 9P host FS sharing seems to be insecure in terms of possibility of escaping to host FS when using passthrough security model even with a FS proxy. I think it is more secure to use a passthrough of a host block device into guest, so I did this using host ZFS zvol + ext3  and it works fine, I can mount it from both host (when needed for maintenance or fast fixes) and from guest.

Now going to customize Heads Linux as a secure guest for surfing and chatting in the Internet.

Some progress already done.

Where can I get grsec kernel with patches to Spectre issue?
It seems such kernel sources have been removed from public though earlier they were available for public.

I am not sure if it is offtopic or not, I wonder how to securely attach USB devices to an ancient Notebook without USB support.

Linux has an USBIP service to passthrough physical USB devices via TCP/IP network.
http://usbip.sourceforge.net/

How can I link OpenBSD client to Linux USB device server via TCP/IP?

For example I can run Devuan on a single board like OrangePI or Olinuxino with Ethernet and USB interfaces and connect Nitrokey Pro 2 to it directly by USB. Then I would like to teleport USB Nitrokey to OpenBSD ancient notebook which has only an old 16bit PCMCIA ethernet card. Though such slot is NOT compatible with CardBus specification required for USB cards, I see it as a security advantage because old PCMCIA does not support DMA (sometimes hijacked by malicious USB devices).

So I conclude that old 16bit PCMCIA ethernet cards like this have not DMA access to computer RAM and cannot readout crypto keys by their blobed firmware unlike all modern cards.

Actually TCP/IP network can be built even on top of RS232 channel which may be even more secure than blobed ethernet card firmware. May be a short cable (like a few centimeters) for connection between notebook and single board can make it more secure?

Though I guess such method is not good enough from security point of view in terms of all Ethernet traffic can leak over side channels like radio emission. But at least if token does private key operations by itself without private key extraction outside the token then only temporary SSH session keys can be leaked via radio channel produced by Ethernet "antenna".

For a guest p9 root FS I used a catalog on the host with a debootstrapped Devuan into it, it worked fine in chroot, but I have never tried it as a full virtual machine with its own boot, kernel and init.

May be, I shall try to just install Devuan into KVM guest from a setup CD at first or at least to try guest Devuan work in Virtualbox by placing the kernel inside the guest, then try to reproduce this on KVM?

I am not sure whom to trust, since some OpenBSD people tell GNU things are partially sponsored by NSA people and GNU open sources are full of invisible backdoors (may be just hardly noticeable interfaces to hardware blobed backdoors). They suggest for security reasons to avoid GNU completely including Linux and Libreboot too. On the other hand they instantly ban from their chat if talking there about hardware backdoors. So I conclude though OpenBSD is more secure by its correct config, correct and high quality program sources, its purpose is not to provide true full security for masses, it is rather to test OpenBSD on masses with backdoored hardware and then use tested OpenBSD software on some actually backdoor free hardware for a very specific VIP persons who sponsors OpenBSD. And such actually secure hardware is not available for public purchase.

On the other hand many people proponent GNU Libreboot can help to avoid some BIOS backdoors.

Is OpenBSD any better in terms of security than modern grsecurity+linux libre kernel like v5.x ? if only a few needed services are enabled and each set of services on a different hardware librebooted motherboard to avoid different security problems of a backdoor escaping chroot/vm/docker/container, etc. Unused kernel modules would be disabled. I guess the less services, module and other software is enabled the less backdoors there are on the host.

I have found OpenBSD nice as a concept but not convenient for an earlier Linux user because of less tools, for example because it misses tools like lsblk to list all partitions.

Say someone will have a dedicated librebooted motherboard for mail server, dedicated for web, dedicated for db, etc. These motherboards will not have any devices attached to PCI/USB/SATA bus except an ethernet card preferably open source if such exists. They will use NFS/iSCSI/NBD/usbip, etc. for accessing disks and other hardware devices on a dedicated host for device sharing. Sure disks and other traffic will be encrypted on hosts free of external blobed hardware devices.

Also a hardware cryptotoken will be used to keep private keys.  Which one would you suggest? Nitrokey Pro 2 or FST-01 ?

Trojans and backdoors including hardware ones can run under root privileges and therefore can change file attributes.

Also they can change contents of file even without help of kernel through drive firmware unless it is a FS like ZFS with checksums, still able to  do changes at vfs level.

Can firmwares of SATA and USB devices access host RAM via DMA? For example to read encryption keys.

Will having a workstation (host) free of devices on any buses except open source Ethernet make it more secure?

Workstation ZFS+Luks -> iSCSI -> a computer used as different buses host, for example as iSCSI target to its local SATA devices.

Can in such case SATA firmwares still access Workstation RAM via iSCSI randomly?

Please let me know, is there on the list:

https://www.openbsd.org/plat.html

a hardware platform open enough to provide a verifiable method to be sure there are no trojans and may be even no backdoors in the hardware and closed firmwares?

What do you think about possibility of backdoors in:
https://www.openbsd.org/armv7.html
?

Some ARM boards are advertised as fully open source working and booting without BLOBs.
For example Olinuxino if I understand it correctly at least without 3D Video.
As another example if I understand correctly Raspberry PI is NOT open source, it requires some closed BLOBs to boot?

Can Olinuxino like board (or may be another brand) work with fully open source software OS like OpenBSD without firmware BLOBs and without closed source drivers?

May be Beaglebone Black is such board?

What about Orange PI? They look very budget.
http://www.orangepi.org/orangepiplus2/
It has a relatively old (which is IMHO good) 4 core Cortex A7 32 bit CPU WITHOUT speculative execution.

What board is secure enough to run OpenBSD just for a terminal console?
Is it secure to use USB ports on such a board to plug crypto tokens like Nitrokey?

Will OpenBSD work with Nitrokey via opensc from OBSD ports?
Will GPG and SSH work on OBSD with Nitrokey encryption?

May be with  a mechanical switch to disconnect keys just after being used to establish a session like SSH?

Is it a good idea to use ZX Spectrum Next (VGA, PC Keyboard) as a serial virtual text terminal to Beaglebone Black running OpenBSD? I guess there shall be less backdoors in resource deficit computer like ZX ?

ZX spectrum or like it -> RS232 -> Beaglebone Black running OBSD with FST-01 attached -> SSH -> managed hosts with hardware tokens like FST-01 attached for keeping private keys