boot.initrd.availableKernelModules and boot.kernelModules are
machine-specific and belong in the user's hardware-configuration.nix
as generated by nixos-generate-config.
nvidia.open is already set by common/gpu/nvidia/pascal (Pascal GPUs
don't support the open driver). nvidiaSettings defaults to true in
the NixOS nvidia module. graphics.enable/enable32Bit should be left
to the user or their desktop environment to decide.
