nixos-config/modules/core/xserver.nix

{ username, ... }: 
{
  services = {
    xserver = {
      enable = true;
      xkb.layout = "us";
      # displayManager.lightdm.greeters.slick.enable = true;
      displayManager.lightdm.greeters.mini = {
        enable = true;
        user = "liv";
        extraConfig = ''
            [greeter]
            show-password-label = false
            [greeter-theme]
            background-image = "/home/liv/Pictures/wallpapers/others/anime-sky-lonely.png"
        '';
      };
    };
  };
}