Create a desktop entry for a webapp using Chromium --app and Nix

.nixpkgs.config.nix

with import <nixpkgs> {};

let 
  webApp = { name, title, url }: stdenv.mkDerivation rec {
    inherit name;

    src = pkgs.writeText "src" ''
[Desktop Entry]
Version=1.0
Terminal=false
Type=Application
Name=${title}
Exec=chromium --app=${url}
NoDisplay=false
StartupWMClass=${name}
'';
    
    phases = [ "installPhase" ];

    installPhase = ''
      mkdir -p $out/share/applications/
      cat $src >> $out/share/applications/${name}.desktop
    '';
  };
in
{
  packageOverrides = pkgs: {
    litewrite = webApp {
      name = "litewrite";
      url = "https://litewrite.net";
      title = "LiteWrite";
    };
}

gistfile1.txt

$ nix-env -i litewrite