@neil pointed me to this: https://developer.android.com/developer-verification
This will make alternative app stores like #fdroid mostly useless on #android devices with a stock rom, since most apps won't install at all, unless also available through the play store.
Being the dev of the #floss #apps #TinyWeatherForecastGermany and #imagepipe, it is unlikely that the apps will be available for devices running a stock rom in the future, since I likely won't share my private keys with G****e nor will I give them a copy of my ID.