nixos-config/hardware/gpu-rpi4.nix

{ config, pkgs, ... }:

{
  hardware.opengl = {
    enable = true;
    setLdLibraryPath = true;
    package = pkgs.mesa_drivers;
  };
  hardware.raspberry-pi."4".fkms-3d.enable = true;
  boot.loader.raspberryPi.firmwareConfig = ''
    gpu_mem=320
  '';
}