No polkit agent?

You can add a polkit agent fairly simply, this is most often used to attaching drives and performing certain write actions on drives.

configuration.nix

  systemd = {
    user.services.polkit-gnome-authentication-agent-1 = {
      description = "polkit-gnome-authentication-agent-1";
      wantedBy = ["graphical-session.target"];
      wants = ["graphical-session.target"];
      after = ["graphical-session.target"];
      serviceConfig = {
        Type = "simple";
        ExecStart = "${pkgs.polkit_gnome}/libexec/polkit-gnome-authentication-agent-1";
        Restart = "on-failure";
        RestartSec = 1;
        TimeoutStopSec = 10;
      };
    };
  };