Hey Google -- If I Wanted An iPhone, I'd Have An iPhone

Google isn't banning the use of "side-loaded" apps (apps you install directly on your device instead of getting from Google Play) ... at least not exactly.

They're banning side-loaded apps that don't have a "certification."

A "certification" that's issued -- of course -- by Google and can be pulled -- of course -- by Google at any time, making the apps non-usable even on devices where they are already installed.

They're turning Android into just another "walled garden" like iOS.

If I wanted another "walled garden" like iOS, I'd be using iOS.

There are alternatives, including both independent phone OSes and "open source" variants of Android that don't depend on, and aren't controlled by, Google. Here's a useful list. I'm not sure how functional, or easy to implement, any of them are, but I'll be looking into that and may come back with recommendations later.