I'm going to upgrade server 2016 -> 2019 and install the ubuntu linux sub system and see if that works. If not then I guess I'll buy a Pi4. Thanks for the replies!
The WSL sub system wont work for USB mining, you'd have to work out how to give it access to USB
The cross compiling windows readme is to produce a binary that runs under windows and of course wont work under WSL.
You'd have to do a standard compile then work out how to give it access to USB.
Alas WSL is not a proper VM and windows drags it down to a crawl.
If you've noticed, it can take hours to compile the MXE system vs 10-20mins on a similar linux machine doing exactly the same cross compiling.
I simply added the readme about how to use it to compile cgminer for anyone who wont run linux, but wants to compile the code themselves.