EU's DMA recognizes the existence of gatekeepers and is supposed to make this kind of behavior unlawful and require allowing 3rd party app stores as an alternative
By extension, Apple might then also accept it for the App Store to prevent third-party stores from having ‘exclusive apps’, as has happened with both Delta (and emulators in general) and UTM SE [2].
[1]: https://developer.apple.com/app-store/review/guidelines/#thi...
[2]: https://mastodon.social/@rileytestut/112791043604056224