> MFC was Microsoft, so that was definitely native

Microsoft reimplemented this stuff from scratch all the time. Not just in MFC itself but Office too.

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.