How to show an AlertDialog triggert by a Firebase Push Notification with go_router?

Question

I have to register a Firebase listener once, like e.g.

      void registerListener() {
        FirebaseMessaging.onMessage.listen((RemoteMessage message) {
          if (message.notification != null) {
            showDialog(
                context: ???,
                builder: ((BuildContext context) {
                  return _PushAlertDialog(message.notification!.title!, message.notification!.body!);
                }));
          }
        });
      }

I don't know when this method is called, so how can I get the current context and do a context.pop() to close the dialog.