(Not OP) cp to copy the /etc/nixos/configuration.nix file, and nixos-rebuild to build the system defined in the file on the new machine.

Or if you're sharing configuration, it's most likely a "git pull" rather than "cp".

Yes, to be specific it's a git clone and a command to apply the flake.

If you're using a flake, can't you apply itfrom git in a single command?

Actually, you can! I always want to clone it either way, so I just do it.