From what I’ve heard about Telegram, you have to explicitly enable end-to-end encryption with another person and you can’t do that in group chats. Shouldn’t that be listed in the document?
It’s very likely that I’m wrong in all this, can anyone familiar with Signal or Telegram confirm?

@mckinley@twtxt.net I’m only familiar with Signal. Signal enforces and requires e2e encryption and is not something you can disable. Signal also encourages users to swap public key fingerprints too (called Safety Numbers) and to do this “Out of Band”.