Without knowing what you mean by "I can't seem to find my groove there" it's difficult to comment really - what's the problem - not finding active communities? People not replying to you?
That sounds like a cracking idea, the suggestion is that something in Apple's ToS prevents this generally - but is that the case, if Signal manages it?
Signal sends notifications via Apple's push notification servers. So I'm still not quite clear what are suggesting. That apps run continuously in the background. each doing real-time polling of their respective servers for notifications? Because your battery ain't going to last long.
Given that I was replying to a message drawing equivalence, you'll see that I was saying that they weren't really equivalent, in that Ukraine hadn't mounted an attack on Russian civilians. Hope that helps.