Built-in push notifications for Android OSS without requiring a separate app

I'm currently using GrapheneOS without Google Play Services, and I've installed the latest Fluxer Android OSS beta (betaoss) through Obtainium. I'm connecting to my own self-hosted Fluxer instance. As far as I understand, the OSS version currently relies on UnifiedPush and requires a separate distributor like ntfy to receive push notifications. I've been using GrapheneOS for several years now, and none of my other apps have ever required an additional push notification app. Everything has worked fine without one so far. I understand that UnifiedPush has its advantages, especially when several apps can share the same distributor. But in my case, I'd have to install and permanently run ntfy just for Fluxer. I'd really prefer to avoid installing additional apps and running more background services than necessary, especially since keeping my device minimal and reducing unnecessary dependencies is important to me.

I'd love to see an optional built-in push notification solution for the Android OSS version, similar to how Threema Libre handles notifications. Ideally, Fluxer would be able to maintain its own background connection and receive notifications without relying on Google Play Services or requiring a separate app like ntfy. The solution should work with both the official Fluxer service and self-hosted instances, preferably without requiring any additional server-side infrastructure. I'm not suggesting removing UnifiedPush. I understand why people might prefer it, especially if they already use it with other apps. It would just be nice to have both options: UnifiedPush for those who prefer it, and a built-in solution for those who don't want or need a separate distributor.

Threema Libre is a good example of what I'm looking for. I've been using Threema Libre on GrapheneOS for quite some time, and its built-in push notification system works perfectly for me without Google Play Services or any additional push app. It maintains its own background connection, and notifications arrive reliably even when the app isn't open. I was wondering if something similar might be possible with Fluxer. Since Fluxer already uses Gateway/WebSocket connections for real-time communication, could some of that existing infrastructure potentially be reused for background notifications on Android? Of course, I don't know whether this would actually be suitable, especially considering Android's background restrictions and battery consumption. I'm just curious whether it could be an option. I'd be interested to hear if something like this has already been considered or if there are technical reasons why Fluxer currently relies entirely on external UnifiedPush distributors for the OSS build.