Nvidia

For Optimus hybrid graphics there are currently two solutions available under NixOS:

1. Bumblebee

Use

hardware.bumblebee.enable = true;

option.

Pros: out of box experience, just start the game via primusrun or optirun wrapper

Cons: some performance penalty, no Vulkan support, things like CUDA and OpenCL are problematic to configure

2. Nvidia PRIME

Use the special script for out of box experience.

Configure NixOS to allow Intel and Nvidia X.Org coexist together, and also to disable nvidia card by default. Requires NixOS version with https://github.com/NixOS/nixpkgs/pull/37369 merged

/etc/nixos/configuration.nix

let
  # nvidia packages to use
  nvidia = pkgs.linuxPackages.nvidia_x11;
  nvidia32 = pkgs_i686.linuxPackages.nvidia_x11;
in
{
  hardware.nvidiaOptimus.disable = true; # disable card with bbswitch by default
  boot.extraModulePackages = [ nvidia.bin ]; # load kernel modules
  # install these in parallel with intel
  hardware.opengl.extraPackages = [ nvidia.out ];
  hardware.opengl.extraPackages32 = [ nvidia32.out ];
}

Similar to Bumblebee, start the game via "primerun.sh".

Pros: better performance, Vulkan and Wayland-only setups are supported. CUDA and OpenCL should work, though CUDA needs additional device creation rule https://github.com/NixOS/nixpkgs/blob/master/nixos/modules/hardware/video/nvidia.nix#L66

Cons: there are still some rough edges noted on the top of script, but otherwise it works fine for me.