I was actually thinking of this post by @WindWarrior (as his alter ego), not your post in this thread or your reply in the other thread. But fair enough, you posted a dump of the APIs invoked, too.
You are right that the iOS/iPadOS version is not based on Electron, I was wrong about that. But they are based on non-native cross platform APIs (Xamarin and React). I assume that these cross platform APIs then call native APIs like SwiftUI.
It looks like they use ReactUI and Xamarin, not SwiftUI directly. Although I reckon ReactUI does call the SwiftUI APIs.