Caveats for builtins.getFlake() inside systemPackages


Searched everywhere and nearly given up hope for a way to install a flake in configuration.nix without switching over completely to flakes (putting some keywords in case people find this in the future).

The way I do this is by using builtins.getFlake in my configuration.nix, like so:

  # configuration.nix
  nix.settings.experimental-features = [ "nix-command" "flakes" ];
  environment.systemPackages = with pkgs; [
    (builtins.getFlake "github:outfoxxed/quickshell").packages.${builtins.currentSystem}.default

Are there any caveats for this method of doing things? Can I pin the input nixpkg channel for every flake that I am installing this way?