[euroclydon]

Yes, although later I learned I could do it in a one-liner. Here nixconfig is a folder with all my nix files:

  tar -czf - nixconfig | ssh 192.168.1.1 \
    'tar -zxf - && sudo cp -r ./nixconfig/* /etc/nixos/ && sudo nixos-rebuild --show-trace '"${rebuild_flag} ${name_flag}"

[yencabulator]

If you're ok with building locally and not on the target host, this is simpler:

nixos-rebuild --flake .#foo --target-host root@foo --build-host localhost switch

[VTimofeenko]

Deploy-rs is a great alternative. It works as wrapper on top of flakes, local (optionally, cross-) building and copying closures to target machine with activation:

https://github.com/serokell/deploy-rs