nixos-config/modules/common/nix.nix

{
  pkgs,
  lib,
  config,
  ...
}:
with lib;
{
  config = {
    nix = {
      settings.sandbox = true;

      package = pkgs.nixVersions.stable;

      extraOptions = ''
        experimental-features = nix-command flakes
      '';
    };
  };
}