So that would result in something like this?

  outputs = { nixpkgs, nixpkgs-unstable, myvendor-scripts, ... }: let
    getModule = {system}: let
      homeManagerModule = import ./modules {
        inherit myvendor-scripts;
        pkgs = nixpkgs.legacyPackages.${system};
        pkgs-unstable = nixpkgs-unstable.legacyPackages.${system};
      };
    in {
      home-manager = homeManagerModule ;
    };
  in {
    getModule = getModule;
  };

config and lib can't be used in submodules then.