Are persistent notifications still a requirement for background apps, such as Signal? One of the reasons I switched to CalyxOS. Not the Signal persistent notification specifically, but it, in combination with all the others I needed running in the BG, made it very difficult to not miss new notifications. I like CalyxOS just fine, but I agree with you on GrapheneOS. I was very excited that it was exactly as I've always wanted android to be (but wasn't), except for those persistent notifications.