We’re talking about stock android having 3rd party app store with permissions to install apps in the background. Yes, you can install f-droid but on a stock android it can’t update apps automatically. It’s not an alternative for normal users. And as long as 3rd party stores are not used by normal users app developers will not care about publishing apps there. What needs to happen is that EU needs to force google (and apple) to allow alternative stores, some heavy weights have to support it and developers need to start publishing apps there.