The problem are the multiple background tasks (one per app), usually not specific and so quite resources hungry.
Check this: https://grapheneos.org/faq#notifications
Discussion
A notifications micro app with background permission (aka Nostr Notification Service) + standardized deeplinks.
Is this a viable solution?
A feature in relays that keeps the state of the app’s notifications what it has and what’s new and then it collects those notifications and when the app pings it in some frequency (e.g. 5/10/60)min it sends the new notifications?
The client does not need to harvest all the stuff on background but just the bundled package at once.