Comment by diarrhea

The Make target I use to deploy in this manner (MacBook to x86-64, single machine) is simply:

    server:
        @echo "Deploying machine (with ssh-agent forwarding): '$(MACHINE)'"
        NIX_SSHOPTS="-A" \
        nix run nixpkgs#nixos-rebuild -- switch \
        --flake .#$(MACHINE) \
        --target-host $(MACHINE).$(DOMAIN) \
        --build-host $(MACHINE).$(DOMAIN) \
        --no-reexec \
        --verbose \
        --sudo

Which has been working well. I admit I do not understand what all of these flags do in detail.

This uses ssh agent forwarding, and then sudo via PAM. That allows for passwordless sudo. Building (well, activating) without sudo is pretty involved last I checked, I could not get it to work.