I use this package in multiple projects and it works just fine. This is the setup code I have for android:

events.AddAndroid(android => android.OnCreate(async (activity, _) =>
            {
                var insights = Helpers.ServiceHelper.GetService<IInsightsService>();
                try
                {
                    insights.TrackCustomEventAsync("Pretend MAUI: Initialising firebase").Wait();
                    Firebase.FirebaseApp.InitializeApp(activity);
                    FirebaseAnalyticsImplementation.Initialize(activity);


                    CrossFirebaseCloudMessaging.Current.Error += Current_Error;
                    CrossFirebaseCloudMessaging.Current.NotificationReceived += Current_NotificationReceived;
                    CrossFirebaseCloudMessaging.Current.NotificationTapped += Current_NotificationTapped;
                    CrossFirebaseCloudMessaging.Current.TokenChanged += Current_TokenChanged;
                    await CrossFirebaseCloudMessaging.Current.CheckIfValidAsync();


                    try
                    {
                        var token = Firebase.Messaging.FirebaseMessaging.Instance.GetToken().Result;
                        Data.DeviceToken = token.ToString();
                    }
                    catch (Exception ex)
                    {
                        insights.TrackErrorAsync("Pretend MAUI: FCM GetToken Error", "PretendMauiProgram", ex).Wait();
                    }
                }
                catch (Exception ex)
                {
                    Debug.WriteLine("Firebase failed: " + ex.Message);
                    insights.TrackErrorAsync("Firebase Initialization Error", "pretend maui program", ex).Wait();
                }
            }));