Along similar lines, I'd say Snikket. I feel XMPP often has quite a bad reputation based on the user experience from 10 years ago, but it's come such a long way and projects like Snikket make it very easy to get started.
Defintely agree here. Glad that Signal finally allowed users to stop connecting their phone numbers to their accounts but man, I wish there was something else.
Telegram just claims to be private, but they can't prove it with technical means, instead they rely on the narrative that they are not data brokers. All the while they have strong connection with suspicious parties like the UAE, and from time to time publish weird announcements like the tucker carlson interview that is also said to have contained a far right dogwhistle