This is very interesting information!
I'd like to note that it's likely that several recommendations used as examples have been superseded with information around https://www.privacyguides.org/en/real-time-communication/ and similar locations, since expressing "use WhatsApp" makes me suspicious (and "use Wire" does not make me more confident): https://www.makeuseof.com/why-i-dont-trust-whatsapp/ https://proton.me/blog/is-whatsapp-safe