i think my main takeaway from Nix/Nixpkgs/NixOS is that the more you learn about it and the ecosystem around it, the faster you oscillate between "this is cool" and "lol this sucks". you never stop oscillating between these two absolutes.
anyway if any nix touchers out there use a deployment tool they actually like, even if you wrote it yourself, please let me know. i am evaluating options for replacing my bad python script
for most people nixos-rebuild with the target host option is sufficient.
if it is not and you want to build one, it should probably use nix-eval-jobs. i think some people like colmena, but I've not tried it because i am among those for whom nixos-rebuild is totally sufficient, even as someone who does cross compiled machines and tiny machines sometimes.