I love it for using klipper. But when I started doing it the klipper pkgs did give me some troubles. You can work around them, but know you might find some issues on the way. Maybe it’s better now, I haven’t really updated that part of my config much recently.

Do know that not all arm devices are equally supported. rpi 3 and 4 are, the rest is community based (see: nixos.wiki/wiki/NixOS_on_ARM). Personally I run klipper on a x86_64 thin client for this reason and because raspberry pi’s were scarce and expensive back then.