I run zfs on my (two) Debian boxes (a thinkpad x1 and a home server). Installing it as the root filesystem was a bit tricky but once it’s done it has been flawless for me. I run the server using 2 ssd in mirror for /etc and all those, and then a couple disks in raidz for data. When one of the root disks died I just swapped it and re synced and was up and running in not time. Unfortunately the laptop only has a single ssd so if that dies I have to reinstall and restore from a backup.
The cool thing is that I can just take a snapshot before messing around and the restore if anything breaks. It has been a really nice experience and I recommend it! I know it’s not the same as an immutable distro, and I tried silverblue but it’s too different from what I’m used to :-)
So do I. Those damn incompatible licenses.