Let’s have that discussion. I’m all ears. Can you name any other pair of frameworks that provide identical functionality, but they are divergent such that each framework is mutually exclusive to its target platform?

And no just because the compass is #ifdef’d out when CoreLocation is compiled for MacOs does not count as “divergent”

OpenGL and Metal?

The various incantations of AI frameworks that have been introduced throughout the years?

SwiftUI vs UIKit vs AppKit vs Cocoa Touch vs Catalyst?

SceneKit vs RealityKit?

I understand as target platform also the various versions of macOS.

How are any of these divergent between MacOs and iOS? You still link against the same framework, and the code is nearly identical between the two except for occasional differences in the hardware limitations.

Go look at any of Apple’s sample code. Outside of UIKit/Appkit, most of their samples target both platforms simultaneously

OpenGL is still supported, and Metal has been around for 12 years.

Cocoa Touch is just the umbrella term for iOS frameworks including UIKit, and Catalyst also uses UIKit.

OpenGL isn't really supported, it limps along for existing code, nowadays depending on the OS version, it actually has Metal underneath, but not what Metal is capable of doing with the hardware.