"according to this question,c++/winrt doesn't support win7, because win7 got no winrt; but this project can run on win7, what happendd? win7 got winrt? winrt deployed to win7?"
need to known why c++/winrt can run on win7 now, thanks
"WinRT" as referenced in the first post you linked is a common short-hand for "Windows Runtime". There are no "Windows Runtime" style APIs supported on Windows 7. Windows 8 or later is required to find support for any "Windows Runtime" API.
In the early days of Windows 8, the "Windows on ARM" OS was called "Windows RT" which people sometimes shortened to "WinRT" which just added to the confusion.
"C++/WinRT language projections" are a way to consume "Windows Runtime" APIs, and can also be used for COM APIs. Kenny's project demonstrates how you can use C++/WinRT in a binary that runs on Windows 10 and down-level on Windows 7. The "Windows Runtime" APIs are still not there. It's just using COM only on Windows 7.