I am not very well educated when it comes to alternative stores landscape. But I do know that in Russia there's now Rustore: https://www.rustore.ru/en which functions by automatically downloading and updating APKs for you.

During the APK install, however, you do see the ugly Android prompt about how this app may be dangerous.

Rustore has its own app payment system, which obviously circumvents Google Play fees.

This works on regular Android phones.

Are there other examples of such stores? Perhaps it's Google's answer to that.