Bundling absolutely is coercion. Apple makes some of, if not the best mobile hardware in the world. It would definitely be reasonable to purchase Apple hardware and run third-party software on it, just like on Macintosh. It would also be reasonable to run iOS on alternative hardware. Neither of those scenarios is possible today because Apple uses the compelling nature of individual aspects to force consumers to accept the entirety of their ecosystem.

No, it's not. There's no use of force or threats. Just like if I have a backyard BBQ, you come over, and I say you can't bring your friend because I don't like him. Just don't come to my BBQ.

A duopoly is not meaningfully better than a monopoly if both participants are doing equally amoral things.

I chose not to use a smart phone for this reason (among many others).

Individual action can be important. Regulation is also a valuable tool. When we discover behaviors that are dangerous, regulating them is absolutely reasonable and moral.

Nah, most of the regulations that people want is just reactionary BS to something or another, in this case, Apple is keeping a certain class of toys out of the App Store. I mean, that's not to say it isn't scummy, but scummy to the level that it ought to be illegal and Apple should be treated like I dunno, PG&E or Old Ma Bell? Not even close.