After the Longhorn collapse, all major ideas that were originally implementated in .NET got redone in COM.
Eventually WinRT doubled down on it, and even if they messed up the whole execution, the main goal of Project Reunion is to bring them into regular Windows, now rebranded as WinUI 3.0/AppSDK.
Parallel to that, many .NET APIs on Windows are COM wrappers at their lowest layer.
Classical Win32 C like APIs, are effectively "stable" since Windows XP