The EU's concern is less "is it technically possible?" and more whether Google's licensing and commercial agreements discourage effective competition.
In particular:
- Google forced every manufacturer to have search and chrome on every android phone if they wanted access to Google Play. No technical reason, just forcing their position. This is why Samsung, despite investing on their browser, was still forced to ship with Chrome. Browser competition on mobile was rigged by default.
- Manufacturers signed agreements making it de facto impossible to ship Android forks not approved by Google. If you want Play Services, you can't ship a fork Android did not approve, no matter whether you're Sony or Samsung. Again, no technical reasons, just forcing their hand.
- Google paid manufacturers so Google Search was going to be the only search option on that phone, preventing competition.
None of these practices make the landscape better for the user or incentivize competition when the game is rigged at contract level.
As for the rest of your post: Europe (but also Japan or South Korea or pretty much the whole world) does not enjoy the corporate laws, abundance of capital and risk prone mentality the US does. Those are problems. Over regulation (or better, inconsistent one across EU) is also a plague.
But that's unrelated with the fact that companies living in monopolies commercially abuse their positions. US regulators themselves have found the practice of paying Apple to ship Google as default search engine to be questionable.