Purchased a cheap USB Host shield which uses a MAX3421e SPI USB controller. I'm currently finishing off the circuit design for the next version of the expansion card and I may put one of those on it. I need to port the USB Host library first to use my proven SPI code. I don't think it will be too complicated. At the moment I checked that the shield works by retrieving the Firmware version number using plain SPI. I'll pick this up again later.

https://github.com/mattuna15/USB_Host_Shield_2.0

https://www.maximintegrated.com/en/products/interface/controllers-expanders/MAX3421E.html