To your first point: I find it telling that your main concern with reducing Apple's monopoly power is that it would elevate Facebook's monopoly power. How about we design regulations that mitigate against monopoly power in all its forms? Then there would be viable alternatives to Facebook and all of the sudden their business model based on hostile tracking becomes completely unsustainable because there's
meaningful competition that actually respects their users. We don't need to be serfs.
To your second point: Apple exerts influence far beyond their consumers. Even though I'm sure this isn't news to you, I'll still point you toward some interesting articles:
https://proton.me/blog/apple-app-store-antitrust
https://lapcatsoftware.com/articles/unsigned.html
Much of this is invisible to the typical resident of the walled garden, but they actually cause a lot of harm to society because of their market dominance. Anybody with a small child is probably aware of the harmful effects of the "dreaded green bubbles" (I'm sure people will try to counter this point with claims that iMessage is somehow more secure / more functional than other protocols. I invite those people to do some research first. I think you'd be surprised at the gulf between your own understanding of iMessage's security vs. reality).