I don’t see any evidence the quality would be higher with a third OS. Do you have any proof of this?
Why do you think Apple would compete harder against two companies, one, say, with 1.5 billion users and another with 2 billion than they compete today against one company with 3.5 billion users?
I disagree wholeheartedly that Apple “isn’t putting the latest technology in their phones.” I think given Apple’s scale and (for lack of a better word) “conservativeness” they often wait to implement features that others at smaller scales will rush out to market. I don’t think a third competitor would change that.
They’re not putting phones on sale and competing for second place because of quality, they’re doing that because their phones are too expensive for the vast majority of users in the market. Not to mention the government actively putting their thumb on the scale for their companies.
There is no reason the EU couldn’t do what China did and support its local companies to make a great smartphone OS. The fact that their conclusion was “the big American companies must be cheating so let’s pull them down” is a pretty good indication of why there isn’t a powerful EU tech company.