Vulnerable devices: myth or reality?

The year is 2022, which means there are about five or six more people reading this text from your phone screen with you.

Yes, that's right, right now.

Obviously, simply deleting (files/photos/texts) does not protect against access by third parties, even children know that nowadays. Nor will reset to factory settings (hard reset) save from prying eyes, because before the device had google/apple installed inside.
What does it mean? That our encryption keys are not so ours:

google/apple has seen them;
downloaded them just in case,
will make them available to the authorities on first request.

Not to mention the fact that the manufacturer has full constant online access to#any of# theirs (not yours, mind you) devices. And that means not only photos and correspondence, but everything on the phone: logins/passwords, microphone, geolocation and even medical tests are at risk.
This is the reality today, and not only for phones, but also computers, smart speakers, TVs, refrigerators and any device that has (1 network access and (2) any operating system on board.