Or Force Google to not track things out of certain apps and giving customers choice to not use those apps at all e.g Gmail, Google Maps etc (or use w/o logging in like you can do on iOS. A good way would be to letting OEMs decide the "Android Account" in Android OS instead of the mandatory Google Account.
Not only opening up of the play store (I am not sure how helpful that would be) but another crucial criminal hurdle here is Play Integrity API [0] and apps using it. By this Google made it apps choose between the notions of "be secured" or "actively decide to remain unsecured".
[0]: Call the Integrity API at important moments in your app to check that user actions and requests are coming from your unmodified app binary, installed by Google Play, running on a genuine Android device
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Yes, Apple does it too but they have proven to not yet started tracking and god as much as I hate Apple and it's walled garden they are still far less distracting and cluttered. Besides they don't just log me into everything and anything like mail etc.
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And the size. Naah, if you are making yet another phablet then I am not even looking to switch. Good luck thank you bye-bye.