Here, let me save you $50. It's the same principle, just a USB breakout box. But one better - capacitive input instead of just switches (of course, switches work too)
There are definitely dozens of existing solutions for PC use, but the console world has long been protective of their gamepads and generally don't allow arbitrary custom devices to be connected unless they're built by hacking up a "certified" device.
This is, to my knowledge, the first time any major console has officially supported custom input devices. It's annoying that it requires a proprietary bridge device rather than just getting rid of their artificial limits on HID input devices that work fine on Windows 10 on their Windows 10 powered appliance, but I guess it is still progress.
The PS3 worked with standard USB HID gamepads out of the box. Too bad Sony dropped this support in the PS4. Oddly though Sony has allowed developers to ship their own custom USB HID drivers in PS4 games, which some fighting games have done to allow people to use their old PS3 fight sticks.
It's not just a USB breakout box. On the back of it, is has standard inputs for assistive devices that map directly to Xbox controller buttons, as well as settings for different input profiles. $100 is a totally reasonable prize, especially in this market.
That's incredible :)
It's USB, so this is going to end up being used for far more than gaming.