Very good points! We've gone back and forth a lot about which platform to use, and basically our conclusion was exactly what you said at the end, there isn't really a great alternative.
We can look into a self-hosted Matrix chat, or any other available alternatives. We've heard some rumors that there might be some Nostr-based options in development. We're open to all of it! But many if not most Bitcoiners are on Telegram already, so we're going with that to start.
Thanks for the honest feedback, and we really do wish there were something better at the moment!