Nixos Gnome RDP Remote Desktop

configuration.nix

{
  # minimized for clarity.
  # Some of these might not be needed. After some trial and error
  # I got this working with these configs. 
  # I do not have the patience to rn an elimination test. 
  
  services.gnome.gnome-remote-desktop.enable = true;

  # Enable the X11 windowing system.
  services.xserver.enable = true;
  services.xserver.displayManager.gdm.enable = true;
  services.xserver.desktopManager.gnome.enable = true;

  services.xrdp.enable = true;
  services.xrdp.defaultWindowManager = "${pkgs.gnome3.gnome-session}/bin/gnome-session";
  services.xrdp.openFirewall = true;
  
  environment.systemPackages = with pkgs; [
    gnome3.gnome-session
  ];

  # Open ports in the firewall.
  networking.firewall = {
    enable = true;
    allowedTCPPorts = [ 3389 ];
    allowedUDPPorts = [ 3389 ];
  };
}

Have to add that this nearly works as of now.
You have to use the gnome-session package from nixpkgs directly (not gnome.gnome-session nor gnome3.gnome-session).
If you encounter a black screen read the official docs on remote desktop carefully, you have to be logged out from any other session to start a remote desktop session.

Yes, as of release 24.11 gnome. was removed from all packages 👍