It depends how you define the market. In the 2001 microsoft case [0], the courts ruled Microsoft had a monopoly over the "Intel-based personal computer market".

Apple has a monopoly over the "M-chip" personal computer market. They have a monopoly over the iOS market with the app store. They have a monopoly over the driver market on macOS.

Like, Microsoft was found guilty of exploiting its monopoly for installing IE by default while still allowing other browser engines. On iOS, apple bundles safari by default and doesn't allow other browser engines.

If we apply the same standard that found MS a monopoly in the past, then Apple is obviously a monopoly, so at the very least I think it's fair to say that reasonable people can disagree about whether Apple is a monopoly or not.

[0]: https://en.wikipedia.org/wiki/United_States_v._Microsoft_Cor....

It isn't just about monopoly or unfair competition. This can also be covered under consumer rights - the Right to Repair. No OS provider should be allowed to dictate what software you can or not run on your own device and / or OS you have paid for.

Courts have already ruled it does in the iOS app store market. You can disagree of course but then you'd be disagreeing with legal experts who know more about anti-trust law than you do.