I'd also recommend to use AppWarden [1] and the Exodus project [2] to verify for yourself what your Apps do behind the scenes.
Regarding an App masquerading as Telegram: Use the Telegram FOSS fork [3] which disables Firebase's trackers.
[1] https://gitlab.com/AuroraOSS/AppWarden
That would still be around 140K people on a population of 7 Billion, which probably is still on the high side. If you do 1000X better, it's still close to meaningless. But if it makes you feel better, of course go for it.
The better advice is to just use your phone as a phone and not install any crap on it that you don't need. Use a PC with a reasonably uncompromised browser like Firefox or Chromium. Even with the default settings, that will keep you out of a heap of trouble and there probably are about 100M Firefox users or so (1.4% of the world population, not so bad).
It has some extra security improvements on top of AOSP and most importantly, the builds are signed and the device can be locked after you install the ROM.