Hi @frhei, I’ve already answered these questions here: Bluetooth LE Smart - Bluetooth Mesh Integration - #3 by vkolotov. Just replace “mesh networking” with “windows generic dongles” 
In short, you are very welcome to help to add support for usb dongles in windows. This could be done vie extending the Bluetooth Manager with a new transport implementation that would work with generic dongles in windows.
Please note, we do have support BT in Windows via BlueGiga transport, although these are not “generic” dongles. Generic dongles are only supported by TinyB transport in linux.
Thanks,
Vlad