foo.nix

myUserSettings = {
  regular = {
    users.users.foo = {
      isNormalUser = true;
      hashedPassword = "bar";
    };
  };
  options-for-modules-based-on-hm = {
    users.users.foo = {
      packages = with pkgs; [some packages];
      enable-bluetooth = true;
    };
  };
}