gnome-control-centre > users > change logo also works now, after removing and re-adding the local user. Now, Gnome desktop is working fine.
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Now, I'm using rEFIt +Devuan+Windows 10 + Utnubu in this PC. So far, good. Thank you to members for the help.

I'm not surprised that gnome won't let you change an icon. The gnome devs are in love with the idea of brand identity. They don't want you to change the way the desktop looks.

Still, 3 warnings due to ratelimiting. I booted another distro to check, which also has 5.x kernel. It shows 7 warnings! wonder if this is something concerning.

Gnome has some rough edges period and does not play well with others.  I have a hard time understanding why anyone would want to use it especially on a distribution whose philosophy leans in the opposite direction of Gnome's.  Classic square peg|round hole thinking.

Case in point:
https://linuxreviews.org/Mpv_drops_GNOME_support

Yes, true indeed. I found it the hard way. But, now I have a Gnome desktop running up and fine except for the slight niggles. It isn't crashing. Gnome-3 is appealing to me, though. I'm using it since long. FYI, I tried KDE 5 Plasma with ascii until upgrading to beowulf. Cinnamon may be a 2nd choice. No fun with minimal window managers & customizing it with conky & stuff.

EDIT: If Plasma desktop can be customized to behave like Gnome-shell, I and many others may be ready to move in.

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Jul  9 08:46:01 localhost kernel: [    3.877003] Not activating Mandatory Access Control as /sbin/tomoyo-init does not exist.
Jul  9 08:46:01 localhost kernel: [    5.481674] urandom_read: 1 callbacks suppressed
Jul  9 08:46:01 localhost kernel: [    5.481677] random: udevd: uninitialized urandom read (16 bytes read)
Jul  9 08:46:01 localhost kernel: [    5.492859] random: udevd: uninitialized urandom read (16 bytes read)
Jul  9 08:46:01 localhost kernel: [    5.494009] random: udevd: uninitialized urandom read (16 bytes read)
Jul  9 08:46:01 localhost kernel: [    5.528119] random: crng init done
Jul  9 08:46:01 localhost kernel: [    5.529210] random: 3 urandom warning(s) missed due to ratelimiting

I have haveged, rng-tools installed.
So far no solution for gnome-control-centre users - cannot change icon.

Case in point:
https://linuxreviews.org/Mpv_drops_GNOME_support

Presently, I have weird issue of nautilus not showing thumbnail previews and gnome-control-centre->Details>Users not able to select  a custom image as my user logo. Silly thing, I know. But, it was working before. It seems Gnome3 on Devuan has some rough edges, hard to troubleshoot.

[ 6298.709434] udevd[16850]: failed to execute '/lib/udev/mtp-probe' 'mtp-probe /sys/devices/pci0000:00/0000:00:1a.0/usb1/1-1/1-1.5 1 6': No such file or directory
[ 6298.770062] udevd[16852]: failed to execute '/lib/udev/mtp-probe' 'mtp-probe /sys/devices/pci0000:00/0000:00:1a.0/usb1/1-1/1-1.5 1 6': No such file or directory

Problem: I cannot select a custom icon for login window in gnome-control-centre. The option to select is not working.

Onward, if I install Gnome3, I assume the udevd worker problem may arise.

Maybe, but that's not the case here. It boots fine with gnome and 5.6 bpo kernel. Here's the package list from that system.
http://distro.ibiblio.org/refracta/misc/pkglist_gnome

Also, desktop-live installed and with 5.6 kernel added works fine.

Probability of /lib/udev/rules.d/ folder getting any changes or addition if I install Gnome? Should I try installing Gnome now? I will look into the list of packages suggested.

Onward, if I install Gnome3, I assume the udevd worker problem may arise.

Maybe, but that's not the case here. It boots fine with gnome and 5.6 bpo kernel. Here's the package list from that system.
http://distro.ibiblio.org/refracta/misc/pkglist_gnome

Also, desktop-live installed and with 5.6 kernel added works fine.

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@fsmithred: I did some dangerous measures to lean the system, instead of re-install. Purged off most of the packages including critical ones. Now, my install has only about 530 packages. Now it boots with linux-image-5.6.x and I get upto the virtual terminal. No delay. Onward, if I install Gnome3, I assume the udevd worker problem may arise. Any input to find out which package will cause the trouble.

OT: Kernel, apt all were purged, essentially making it a broken system. Then, I boot into the another linux installation and extracted filesystem.squashfs from the refracta iso provided. Downloaded apt & related dependencies in chroot environment, copied to /var/cache/apt/archives of Devuan. Afterwards, installed it with dpkg in chroot Devuan installation.

apt-list of packages:
http://paste.debian.net/1155414/

Debuser2018 wrote:

thermald, has only systemd script /lib/systemd/system/thermald.service . No /etc/rc* or /etc/init.d/ script for startup.

You can convert a systemd unit file to a sysvinit script with sysd2v.

Then copy your_init_script to /etc/init.d/ Make it executable (+x). Change the owner:group to root:root.

You'll then need to run:

sudo update-rc.d your_init_script defaults

to set up the /etc/rc* files (which are symlinks back to your_init_script)

and

sudo invoke-rc.d your_init_script start

to start the daemon immediately.

sudo service your_init_script start

should also work.

thermald, has only systemd script /lib/systemd/system/thermald.service . No /etc/rc* or /etc/init.d/ script for startup.

You can convert a systemd unit file to a sysvinit script with sysd2v.

Debuser2018 wrote:

I am going through boot messages while udevd got stuck. It says  "1 urandom warning(s) missed due to ratelimiting". Is this related to the entropy bug too? I already installed haveged.

I've seen that warning on systems that boot. I don't think it's a problem.

I added bluez and then blueman, rebooting after each. Still can't reproduce the problem. You may need to install things one at a time and see which package breaks it.

But, that's all I added (even in apt history.log). When I installed with beowulf-desktop-live and beowulf-netinstall ISO's, I installed linux-image-5.6.x and just rebooting to the OS results in the udevd worker getting time out.
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But, is there a way to strip off the Beowulf installation to minimal basic install, so that I can test if the udevd problem persists? Currently I've removed Gnome, libx11-*, xcb0 and other X related packages. If there is a way, I can just install the default package lists only, then we can find if the problem disappears.

**Unrelated** : thermald, has only systemd script /lib/systemd/system/thermald.service . No /etc/rc* or /etc/init.d/ script for startup.

I am going through boot messages while udevd got stuck. It says  "1 urandom warning(s) missed due to ratelimiting". Is this related to the entropy bug too? I already installed haveged.

I've seen that warning on systems that boot. I don't think it's a problem.

I added bluez and then blueman, rebooting after each. Still can't reproduce the problem. You may need to install things one at a time and see which package breaks it.