I use the #FOSS app #Molly for Signal, from #FDroid. It's good.
I have recently installed ntfy for use with Moshidon, so I'm considering switching to the UnifiedPush version of Molly. It's in the Molly FOSS repository for F-Droid.
I'm not familiar with most of that stuff, but are you saying that Molly's UnifiedPush implementation doesn't work like you expected?
I have ntfy. Works well for me, but I guess ymmv.
@ErikJonker Telegram is not comparable with Signal; stop comparing them. Telegram is a social network app. Compare it with Facebook and its encrypted messages with Facebook Messenger.
That said, neither Signal, nor Telegram are usable to me, since they require a phone number for registration. I've been using Wire for a while and it sucks - but is at least usable.