@cayce I don't know about your clone but I have an official Wii U controller and it is definitely Bluetooth. It is an odd version of Bluetooth though like the Wiimote. I have no experience of making it work on my Pi4 but on a Windows PC they require some fiddling/extra drivers. I've been using a Wii U Pro controller for CEMU on my PC.

I understand that they can be used as a wiimote (wiimote and nunchuck?) and I would like to look into using it as such when 64bit Retropie/Dolphin comes around. That will be some time off though.

I was having the same problem. I set the home button on the Wii U pro controller as the hot key. Now when I press down the home button and start It does the same thing as start and select use to do, Exits emulator.

I would be surprised if this was successfully done by someone. The video for the screen is streamed over a proprietary 5 GHz radio. A gentleman in a previous post said it's based on 802.11n and he could very well be right. Still I think it may be possible through a custom USB adapter of some kind, though the 480mbps throughput limit may turn out to be a constraint, not sure. Is it possible? I believe so yes. Is it something easy to do, almost certainly not. You would probably need to find an engineer to design a custom USB adapter to communicate with the pad.