That doesn’t do what you think it does.
It does cover some stuff (see their latest report: https://source.android.com/security/reports/Google_Android_Security_2018_Report_Final.pdf ) but they don’t/can’t check or “guarantee data that is supposedly sent to “A” is not actually going to “B””.
Also keep in mind that this is not dependant on “where you’ve installed the apps from” (eg. apps using Facebook SDK and sharing your data with Facebook without your consent: How Facebook tracks you on Android - media.ccc.de were “clean” apps installed from Google Play store ).