During the installation process I always select manual partitioning (which is mandatory for me as I have a triple boot system), so I can choose the proper partition for /.
Being used to installers of previous installations would just make use of an existing swap partition (instead of reformatting it), I honestly didn't pay attention to what the Devuan-installer was doing with swapspace.
Will have an eye on that from now on.

Too bad that my experience is different from yours. Otherwise I could have just applied your fixes and most likely get it running.
On my system, elogind/libpam-elogind is already installed while consolekit is not.
Still, there is something wrong with slim as I just see a blank wallpaper.
My personal workaround is to use another DM and I can happily live with that.

I just wonder if I am the only one having problems with slim as it seems to be the default DM. At least I hadn't seen the option to choose another one during the installation (I might have overlooked it though).

I booted Devuan again today (now yesterday) and there was the same wallpaper.... but this time with a greeter.
I could log into the DE without any problem. Everything working as it should (as fas as i can tell).

The thing that keeps puzzling me:  I hadn't changed a single thing in this system.

The only thing I can think of is that it could have to do with the swap partition which is also used by Debian Bullseye.
During the installation of Devuan, the swap partition seemed to be recreated again by the Devuan installer and that must have caused a problem for Bullseye.
After the installation of Devuan, the start-up of Bullseye took a lot longer than usual and from what I've read, there was a problem with swapspace (I can write down the message if required).
When I was finally in my DE (in Bullseye), I started the taskmanager and noticed that there was no swapspace available.
So I fixed it with swapon. (But this problem is still present in Bullseye after every reboot.)
And since that swapon in Bullseye, I could finally log into Devuan without any problem, as the greeter is being shown.

I don't see any connecting link between both issues and I have no clue if that actually had to do with it.
I can just report what I've witnessed.
Now I just need to fix the problem in Bullseye (at least until I will completely replace it with Devuan).

I can provide the output which I saved in a txt-file but as the problem seemed to have solved itself, it's probably not of interesting anymore.
If it still is, let me know.

Thank you.

Ok, then there was a misunderstanding in the way that a connection was made to the internet. I never use wireless and to me reading about a "functioning ethernet connection" was synonymous to a working internet connection. My bad.
Still, to successfully perform an installation including a DE via a netinstall.iso, a working internet connection is an absolute necessity. Otherwise I wouldn't have gotten anywhere.
And having mentioned that the install went smoothly (and that the install of Debian Bullseye went uneventful, too), I assumed that it was obvious to everyone that internet access was not the problem (otherwise the installation would not have been possible at all).
That's why I wonder that you wrote this...

... as I had already mentioned in my very first post that the installation (including DE) was completed smoothly and uneventful.

If you read my 2nd post again, you will find that there was no lack of response.
I answered his only question ("what  is your video card?") and also gave feedback about why it can not possibly be missing drivers for the chipset governing the display (--> background wallpaper of the DM present; install of Debian Bullseye went without a hitch).

That's why I completely disagree with the point of your comment as it addressed something that I had already explained.
Can you now understand that I found it inappropriate and rather aggressive?

Accepted. Let's forget about it.

I was about to try the startx-suggestion but as I could log in all of a sudden (see above), I didn't carry it out.
But I looked into ~/.local/share and was surprised to not find an xorg-directory (only an icc-directory).

Thank you everybody for your support so far.

It doesn't have separate video card but an integrated chipset (Intel(R) 4 Series Express Chipset) on a 13 year old laptop. So it's been around for quite some time.
And as the background image of the login screen is being displayed (but only that), I would have guessed that it's not an issue that has to do with the drivers for above mentioned chipset.

The install for Debian Bullseye was not a problem whatsoever.
And during the install of Chimaera, I didn't see anything that would point to missing drivers or anything of the like.

I've installed lightdm afterwards and configured the system to use it instead of slim but to no avail.
Still no greeter, just a different background image.

(Did I expect too much in assuming that the Devuan installer is pretty much the same as Debian's minus everything that has to to with systemd?)