> Legally in the United States you wouldn’t be able to do this with Apple today when applying that law because Apple does not have monopolistic market share

That depends on how you define a market. Apple has a monopoly on app distribution to iOS devices. The argument for defining it like is is persuasive because in the Microsoft case you could at least install an OS from another vendor. You can't do that with an iPhone. Your only relief is to buy a new phone from a different manufacturer.