Eirikr70 only a minority of apps support UP, it wouldn't be the primary solution. We do provide the same ability as "stock" to use the primary app implemented push system of FCM simply by installing sandboxed Play Services. People see it as something frightening or somehow defeating GOS but it doesn't and isn't.
The real solution isn't an OS level one, it's an app developer one. I mean Molly implemented FCM push without play services. It is possible but as with the issues regards Play Integrity when most app devs just use the standard development kits it's easier for them to implement and forget the standard FCM.
VEECCdYKYi see above, it's all academic if app developers don't implement it.