The precedent that would set if the Apple/Google is forced to distribute alternative app stores via App Store/Play store. No downloading the apk and turning on

The precedent that would set if the Apple/Google is forced to distribute alternative app stores via App Store/Play store. No downloading the apk and turning on installation from Unknown Sources to install it. This would also enable alternative stores on Xbox/PlayStation/Nintento etc. Steam inside Epic Games store and vice versa