Ok, I'm fed up with this, just read something about android constantly monitoring your phone's location, now it's time to shut this up.

Would you please be so kind and share information on which alternative "privacy-first" OS I could use and how to flash my device? For all I know, it runs a custom HTC modified OS. I'm quite unfamiliar with all those things gravitating Android. Heard about Cyanogen mod but that's about it.

What about compatibility with apps downloaded through the play store? (thinking about Threema) I would also need compatibility with WhatsApp (yeah, sucks, I know, but hard to convince regular people)

Thank you all :)