I'd like to hear more about this. Can you distribute on the official Google Play store and incorporate GPL code? Is this allowed because there is an alternate m

I'd like to hear more about this. Can you distribute on the official Google Play store and incorporate GPL code? Is this allowed because there is an alternate means of installing apps (side loading) which you must make available to all users? I'm curious if a developer can incorporate GPL code in their app and make it available only on Google Play or the Amazon App Store while supplying the relevant source code (or object files) — but not making the unsigned/unprotected APK available to the public.