I spent last night fighting with aforementioned combination. The actual install process went relatively easy. Copy contents of Devuan 4 netinst dvd into usb stick, with dd, after that when you finally manage to get into the boot menu, it is pretty straightforward. After the install there were all kinds of complications.

First i noticed that there is no sudo. Well, "Ubuntu-style sudo" is annoying but i would like to be able to say:"sudo /sbin/shutdown -h now" instead of "su -"+"/sbin/shutdown -h now". So i'll copy the .deb -file containg sudo and some other files from desktop to stick and from stick to laptop.
After some tweaking i decide it is time to "/sbin/ifup eth0" and after that "apt-get update;apt-get upgrade -u". Then apt starts to complain. I remember "oh yes, the iptables rules could be outdated, lets edit them so that the name servers of my ISP are included". Then "nefilter-persistent restart". Still apt complains. And i notice that the rules haven't changed. OK, i'll say "/usr/sbin/iptables-restore /etc/iptables/rules.v4" . Now the dns-rules are ok, apt doesn't complain.

When trying to install stubby there were some complaints. So i edit the configuration files and create necessary users. Something else caught my attention so i forgot stubby for a while,

Finally i get to log into x . I say "su -" so that i can do some things, including editing sudoers for that shutdown-thing. I can't get in as root. I guess i remember the password wrong. So i reboot with install stick and enter rescue mode and change the password. I have to do that 4 times in a row and still can't get in as root.
I can be clumsy sometimes but not that clumsy. And there were also an episode where something went wrong with grub. Not sure why, but i didn't get into grub menu. Fortunately i manage to enter commands to load grub.cfg from /boot-partition.

When the sun rises i have become so exhausted that i decide to go to sleep and continue fighting another day.
No sure if i got stubby working or not.

There were always something. But I like to think that the situation is not hopeless.
I already did some searching with Google and duckduckgo but haven't found anything useful yet.

UEFI settings are 1 line of investigation and commandline options another. And trying more recent version of Devuan the third.

Last weeks i have been mostly listening to My Dying Bride. For example:
https://www.youtube.com/watch?v=2P-vaGs8GRg  The Raven and the Rose (Live)
sounds interesting.

I have been planning to reinstall os to my desktop so when i get that done, i hope that all the weird behaviour goes away or i find out if my hardware is faulty.

I have taken account the path. I think the problem are some non-visible characters in the lists. Making the hash list in many parts seemed like a good idea for a while but now i'm not so sure anymore. Maybe i'll upload the full file or partials into pastebin some day.

https://www.youtube.com/watch?v=bjOG0meK-vk Junkhead (Alice In Chains)

beginning of song sounds a bit like Black Sabbath. Although singer is not Ozzy.

I'll answer to myself:it is possible.

Last night, while trying to distillate the essential parts of the problem, it seems that i was not precise enough. Noise is needed along with the signal.
Another try:

Try 1

mount /dev/sdaX /mnt/a -o ro
mount /dev/sdaY /mnt/b -o rw

cp /mnt/a/*.xx /mnt/b
cp /mnt/a/*.yy /mnt/b
cp /mnt/a/*.zz /mnt/b
cd /mnt/b
sha512sum ./* > sums.txt
sha512sum -c sums.txt

sha512sum says the files in the list are all OK
after that another round:

umount /mnt/a
rm -rf /mnt/b/*
mount /dev/sdaX /mnt/a -o ro
cd /mnt/a
sha512sum ./*.xx > part1.txt
sha512sum ./*.yy >> part1.txt
sha512sum ./*.zz > part2.txt
cp /mnt/a/*.xx /mnt/b;cp /mnt/a/*.yy /mnt/b;cp /mnt/a/*.zz /mnt/b;cp /mnt/a/part*.txt /mnt/b
cd /mnt/b
mv part1.txt sums.txt
cat part2.txt >> sums.txt
sha512sum -c sums.txt

and only .xx files receive OK from sha512sum -c .
.zz files are supposed to change more often than .yy files and .yy files are supposed to change more often than .xx - files. So it seemed like a good idea to split the file sums.txt in 3 parts. Or to be more precise, build the file sums.txt from 2 or 3 files.

I tried to look at those .txt files with hexdump. I may have found the characters that cause the problem with "sha512sum -c" but i haven't figured out how to get completely rid of them.

Fortunately there are many dm:s available even in Devuan. But there's another thing:
i would like to continue using xfce but it's dependencies are starting to bother me. When i install xfce by saying "apt-get install xfce" , some package draws in avahi and libavahi. I did some googling and noticed that it is recommended to remove avahi because it is considered as a security risk.
And then there's also libcups3. When most of things i do with a computer are reading email and watching Netflix and youtube videos, why do i have to run a print server also? OK i'm exaggerating a bit , libcups is not same thing as cups but i wonder why it is needed?

From "man sudoers" i found an example which mostly fits my needs. As i suspected, i have to say the needed commands before "%sudo". And i can also restrict group sudo to rm and /usr/sbin/usermod . It is not everyday that i need to edit /e/sudoers so it took a while. Maybe i shouldn't quit my day-job.

So i'm the only one here who has broken slim?-)

I have noticed that GRUB can loop mount files. So i can dump my "/" into a file and use grub-mkrescue to make an .iso which contains that file.
Unfortunately something happened to my old computer so that it became non-compatible with GRUB. So i have been stuck with isolinux and pre-existing distros.
My current computer should be in better shape so i would like to think that using GRUB is an option. Maybe i try that Refracta-thing some day.

I know for a fact that there are some problems with the modified filesystem.squashfs . When i chrooted into the directory that contained extracted contents, and tried to do stuff(removing and installing packages for example), i received enormous amount of complaints from sudo. I got them fixed, for example owners and rights of /usr/bin/sudo and contents of /etc/hosts . But either there's still some things unfixed or collateral damage caused by the commands i used to fix sudo.

It seems that i have a tendency to break slim
It would be very useful to find out how to fix it also.