Qt may lack MSMF support but it can do directshow.
“viewfinder” is what you want.
https://doc.qt.io/qt-5/qtmultimedia-windows.html
if that really doesn’t suit you, I’m sure there are recipes for accessing MSMF/DShow directly.
you can’t use OpenCV for the level of flexibility that you require. OpenCV does not have a list of video devices.