Most bitcoin communities and projects have very active telegram groups.
I also prefer more private and decentralized solutions but at the same time I'm pragmatic and use what works in the most privacy preserving way (FOSS client, orbot proxied, sms4sats burner phone).
Most simpleX / matrix groups are dead in comparison. Ignoring a discussion about FOSS tg clients does not seem that productive to me.
Early nostr development even started as a Telegram group that is still very active.