Something in the news today that reminded me of the discussion in this thread:
Cybersecurity experts who have examined how NSO’s Pegasus spyware works say the software does not discriminate between encrypted messaging apps and can access pretty much everything on an infected phone. They say Telegram, as well as WhatsApp, Signal and other messaging apps promising end-to-end encryption, are in effect rendered powerless if the device on which they are installed is infected by hacking software as powerful as Pegasus.
The point is that end-to-end encryption does not save you if you cannot trust the operating system. You need an operating system that you can trust first.