Systems with a recently generated hardware-configuration.nix may instead specify only nixpkgs.buildPlatform, or fall back to removing the nixpkgs.hostPlatform line from the generated config. Specifies the platform for which NixOS should be built. Specify this only if it is different from nixpkgs.localSystem, the platform on which NixOS should be built. In other words, specify this to cross-compile NixOS. Otherwise it should be set as null, the default. See its description in the Nixpkgs manual for more details. Ignored when nixpkgs.pkgs or hostPlatform is set.

null

{
  system = "aarch64-linux";
}