system/hosts/home/configs/boot.nix

{ config, lib, ... }:

{
  local.nix.allowUnfreePackages =
    lib.optional config.boot.loader.grub.memtest86.enable "memtest86";

  # Use the GRUB 2 boot loader.
  boot.loader.grub = {
    enable = true;
    device = "/dev/sdb";
    # memtest86.enable = true;
  };
}