I set up my own configuration so that I could switch to runit and/or the GNU Shepherd on a systemd distro.
It's incredibly niche and isn't necessary for Devuan, but I want to share it to show that it's possible to switch init systems, with only a slight loss in functionality when none of the software is recompiled:
https://codeberg.org/AwesomeAdam54321/LL_Runit_Scripts

The only things that don't work are systemd-logind(obviously) and polkit. I probably have to use elogind and recompile polkit to make it work properly.

I have to run sudo commands when I want to shutdown, reboot or mount flash drives but apart from that it functions normally.
If you have any tips or advice on this topic, it would be gladly appreciated.