Cppwinrt is in maintenance mode[1]. Cppwin32 is abandoned (with windows.h as the official alternative). It is now possible to deploy WinUI 3 apps as single files in C#[2] but not in C++. From experience, the entire C++ side of WinUI 3 documentation is underbaked to the extent that the easiest approach is to read the C# documentation and attempt to guess the cppwinrt equivalent (as docs for cppwinrt are not really... there).

I don’t know if they’ve really abandoned C++ entirely—the compiler team certainly hasn’t, that’s true. But the above doesn’t feel like first-class support.

[1] https://github.com/microsoft/cppwinrt/issues/1289#issuecomme...

[2] https://learn.microsoft.com/en-us/dotnet/core/deploying/sing...