NixOS-Config/modules/system/devices/bluetooth/default.nix

{ ... }:
{
  hardware.bluetooth = {
    enable = true;
    settings = {
      General.Experimental = "true";
      Policy.AutoEnable = "true";
    };
  };

  # Lingering helps keep headphones connected
  systemd.tmpfiles.rules = [
    "f /var/lib/systemd/linger/jimbo"
  ];
}