Meanwhile on Telegram everything just works more or less as is has always done.
If I click on settings I get a "menu" called "Passcode & Face ID". There's a button saying "Turn Passcode On", and a help text saying: "Note: if you forget the passcode, you'll need to delete and reinstall the app. All secret chats will be lost."
While I personally have big questions around the encryption in Telegram I think Telegram takes a much more effective approach towards making it available: by default it is just a very good messaging application that is a good replacement for Facebook Messenger and WhatsApp and almost everything else except Signal.
On top of that it provides secret chats which are end to end encrypted (and can also be set to automatically disappear), and an option for deleting all my data if I don't log in within 1, 3, 6 or 12 months.