You were right :) look at my username! Installation was very interesting - using kexec to swap the current loaded kernel to a NixOS live image, and installing it right over the current system surprisingly worked flawlessly. One reboot for an entire install (I might end up writing a post in !NixOS@infosec.pub about it).

Setting up lemmy was a bit more difficult though, as the lemmy module is currently in the middle of a pull request to improve it, so I had to do some hacky trickery.