With the recent banning of Huawei from Google services, it's got me wondering about one important thing, and that's push notifications.
It seems that Apple and Google have their own (what I'll call) "root level" push notification servers that are the single point at with push notifications are distributed to a phone (at least from what I can tell), with these being APNS and GCM (or FireBase now)
While there are push notification services, such as Pushover, aimtell, OneSignal, AirNotifier etc, my understanding is that they still use these main "root level" services by the 2 giants.
Are there any other root level push notification services available that could be drop in replacements if a full ban on Google services was to be dropped completely for all, past, present and future Huawei mobile devices?