The Bliss Box team has just added a single-player version of their controller adapter to their webstore called the Gamer Pro. This device utilizes their existing controller adapters which are available for pretty much every console out there and converts the signal to USB.
Using their custom software, the Gamer Pro can be switched into modes compatible with the Switch, PS3, Xbox and even regular USB devices like the Raspberry Pi and MiSTer.
Also available is a breakout board for anyone looking to use their high-quality adapters in their own hardware project:
Personally, I’d like to see this integrated into a MiSTer IO board! The Bliss Box team already has years of experience making great breakout cables, so why not be able to use them directly on the MiSTer, with no USB conversion and extremely low lag! Hopefully MiSTer team members will take notice and give this a try.