Bliss-Box released its Bridge.
What is the Bridge?
The Bridge Connects a 4-play in single mode or Gamer-Pro and sends controller data to a console. The Bliss-Box Gamer-Pro and 4-Play are USB devices that are intended for a USB host. However in the same way the BlisSTer works, all Bliss-Box devices can speak a universal protocol over two wires. The communication can take place over the USB lines without disturbing USB hardware. When you connect the Bliss-Box Bridge to a Gamer-Pro or 4-Play, it begins sending controller data at a fast rate of 500us per request. That is twice as fast as the fastest USB poll-rate. The Bridge takes this data and then speaks to the console. The console now controls the polling rate (typically 16ms) and while the console waits for the next poll, the Bliss-Box gathers the payload.
So what does this mean? It means you can use any controller you want, on any console...
Where can I get one? Bliss-Box.net
What do I need? Other then a drawer of controllers and rack of consoles, you need a Bliss-Box Gamer-Pro or 4-Play. that is how you read the controller, the Bridge talks to a console.
So far 7 cables have been made but you can make your own if you have the skills. I comes with the USB so that one it ready out of the box.
examples:
paddles on the switch
https://www.youtube.com/watch?v=nMpZM_aIm24
Analog stick on the intellivision
https://www.youtube.com/watch?v=wJeOz1Dzmds
pippin on saturn
https://www.youtube.com/watch?v=KelYLpxnJTk&t=9s
wii draw on mario paint
https://www.youtube.com/watch?v=RZHlu1XgETQ&t=9s