Not mobile-only, iphone-only. This is a good example of how ios is a seperate market and Apple has the monopoly.
Are there any non-Apple created apps with large user base that are truly iOS only? There probably are, but as an android user, I don't know.
Particularly when the app in question is more technically demanding and has greater need to use platform facilities.
If it's a bog standard CRUD app, that might be reasonable to take multiplatform on launch day, but on the other hand something like touch friendly version of Final Cut Pro would be much more challenging to have both iOS and Android versions of right out of the gate.
Regulation should be more on punishing lock-in past a threshold of customer harm. Basically forcing the opening of iMessage to other platforms and perhaps portability for iTunes content?
Nobody uses Clubhouse on any platform. Being forced to listen to long-form narrations of bullshit LinkedIn wall posts is an excruciating form of torture.
If you want to vote with your feet, buy apps on your platform and spend money through it.
The PlayStation is a separate market and Sony has the mOnOpOlY.
The Switch is a separate market and Nintendo has the MoNoPoLy.
The Xbox is a separate market and Micro$oft has the m0n0p01y.