Intel Graphics
From NixOS Wiki
Video acceleration
To enable hardware (GPU) accelerated video decoding and encoding you need to add additional entries in hardware.opengl.extraPackages (see "accelerated video playback").
12th Gen (Alder Lake)
X Server may fail to start with the newer 12th generation, Alder Lake, iRISxe integrated graphics chips. If this is the case, you can give the kernel a hint as to what driver to use. First confirm the graphic chip's device ID by running in a terminal:
$ nix-shell -p pciutils --run "lspci -nn | grep VGA"
00:02.0 VGA compatible controller [0300]: Intel Corporation Alder Lake-UP3 GT2 [Iris Xe Graphics] [8086:46a8] (rev 0c)
In this example, "46a8" is the device ID. You can then add this to your configuration and reboot:
boot.kernelParams = [ "i915.force_probe=<device ID>" ];