Don't modern versions of Windows contain at least 5 different widget frameworks? Like, Win32, Ribbon (I think engineered for Office as you said), WinForms, WPF, WinUI 1/2/3... I think Apple just has Cocoa (Carbon is long gone), AppKit, UIKit, and SwiftUI.

You (rightly) forgot about UWP, "universal windows platform"

Eh, I forgot if UWP was a widget framework, I thought WinUI 1/2/3 included the WinRT stuff.