I'd just like to interject for a moment. What you're referring to as iOS, is in fact, EU/iOS, or as I've recently taken to calling it, EU plus iOS. iOS is not an operating system unto itself, but rather another component of a fully functioning EU/iOS system made useful by European Union regulations forcing the ability to offer alternative app stores, browser choice, more control over default apps…
The European Commission is going through Apple’s OSes feature by feature, with the help of interested parties and industry collaboration, and deciding where the API lines should be drawn. It’s absolutely fascinating.
And remember, Apple brought all of this on itself through its years of misconduct and inability to follow the law.
Don't miss the 30 pages of proposed specs in the PDFs here (summarized in screenshots here; no alt-text, follow through to original link): https://digital-markets-act.ec.europa.eu/dma100203-consultation-proposed-measures-interoperability-between-apples-ios-operating-system-and_en