I've also followed these instructions above. But I migrated from Ubuntu Mate 18.04 to Beowulf. It was a mess but fun! How nice to run /etc/init.d/networking again!

Some of the hitches were with Elogind, which wouldn't configure during install but after uninstalling systemd it went ok. And a couple of others like avahi.

I couldn't have done it wihtout this thread and the app aptitude. So far I've just done aptitude safe-upgrade since aptitude full-upgrade had way too many conflicts. And I've also just enabled the repo beowulf main yet. But I will continue....

So you can migrate from Ubuntu to Devuan too!