nixpkgs/nixos/modules/system/boot/loader/efi.nix

{ lib, ... }:
{
  options.boot.loader.efi = {

    canTouchEfiVariables = lib.mkOption {
      default = false;
      type = lib.types.bool;
      description = "Whether the installation process is allowed to modify EFI boot variables.";
    };

    efiSysMountPoint = lib.mkOption {
      default = "/boot";
      type = lib.types.str;
      description = "Where the EFI System Partition is mounted.";
    };
  };
}