Google talks beta-testing on the Play Store, announces “Early Access” feature
To promote up-and-coming apps, Google will also add a new Google Play Early Access category. This will basically be a list of open betas that one can opt into, but hand-picked to represent the most promising and interesting new apps.
Additionally, developers will get a set of very helpful aggregator tools, which show them how many devices their apps are stable / unstable across, and Google's Firebase Test Lab will automatically send the devs screenshots of their app, running on different devices, Android builds, and language settings, so they can hunt for layout issues across the board.
In a nutshell – you can now gain early access to hot apps and the quality of software across the Play Store should continue to improve in the following months.
Stability statistics for developers
source: Android Developers
Things that are NOT allowed: