I saw this as part of https://docs.microsoft.com/en-us/windows/uwp/cpp-and-winrt-a... (and the previous cppwinrt github project) but I haven't dug too deeply. I wonder if the restrictions are too limiting. Any bare-bones win32 example of using it in a simple cpp file? I plan on doing a poc myself soon.

Using WinRT stuff in a Win32 app is quite simple. Add windowsapp.lib, #include "winrt/Windows.Foundation.h", and call winrt::init_apartment();. There's no easy way to embed Xaml controls, though. I think the only option would be to have a separate Xaml window, get its HWND, and SetWindowLong+SetParent to force it to be a child window.

There's this: Walkthrough: Hosting WPF Content in Win32[0]

That does use C++/CLI though, but I'm sure you can play around with the embedded api if you really want a pure C++ solution.

[0] https://docs.microsoft.com/en-us/dotnet/framework/wpf/advanc...

WPF ≠ UWP XAML, which is what the EdgeHTML control is.

Well, the controls in question here are WPF and WinForms hosts for UWP controls, so if you can host WPF then you can use the UWP host control to host UWP content. Yeah, its a bit roundabouts, but I think it is the only supported way right now.