I just heard about C++/WinRT and I'm surprised that C++ has this runtime which adds high-level class wrappers like .NET does. But I don't want to distribute my apps as UWP apps. Can I use C++/WinRT in a non-UWP application?
Yes, C++/WinRT (and WinRT in general) is not limited to UWP apps. You can write console apps, desktop apps, services, and even drivers with C++/WinRT. C++/WinRT is a header-only library. It's only requirement is that you use a modern C++ compiler that supports C++17.