I was just thinking more or less along these lines - I haven't been in mobile apps for a few years now, but back then my impression was -
SwiftUI is great for "surface level" UI, that has some basic data bindings - think a basic CRUD app, which needs some navigation, and the ability to scale across the smallest iPhone to the largest macOS screen, from touch gestures to mouse input.
If you ask anything more of it, then you need to start branching off into specific libraries / tools / frameworks (UIKit, CoreAnimation etc) - which is much easier now too, but you'll always have a bad time if you try to mix the two in a single "view" / "frame".
SwiftUI is great for "surface level" UI, that has some basic data bindings - think a basic CRUD app, which needs some navigation, and the ability to scale across the smallest iPhone to the largest macOS screen, from touch gestures to mouse input.
If you ask anything more of it, then you need to start branching off into specific libraries / tools / frameworks (UIKit, CoreAnimation etc) - which is much easier now too, but you'll always have a bad time if you try to mix the two in a single "view" / "frame".
I'm not surprised that's still true today.