I even "DE hopped" using NixOS, trying out 3+ different DEs for fun, and once I was done I just had to revert to an older generation, no nasty leftovers.
I use NixOS unstable on my desktop/work machine, but when I just started using NixOS, I even regularly hopped between the latest stable release and unstable.
Another fun related feature: NixOS really only requires /nix and /boot to boot. So, some of us just nuke everything except /nix, /boot, and /home on boot:
Another fun related feature: NixOS really only requires /nix and /boot to boot. So, some of us just nuke everything except /nix, /boot, and /home on boot:
https://grahamc.com/blog/erase-your-darlings