One of my gripes with my original 8BitDo Ultimate 2.4G Controller is that Steam Input cannot see the additional buttons on the back, but it seems that with the latest firmware updates to the 8BitDo Ultimate 2 that 8BitDo are solving the situation.
The problem with the original is that they're not full hardware buttons, so they cannot be mapped normally and need the software from 8BitDo. So that's something that seemingly cannot be solved but for their newer hardware that doesn't seem to be a problem.
As noted on the Steam forum in a post talking about the 8Bitdo Ultimate 2, a user noted improvements in a later firmware update for it:
Bumping this again. With a recent beta firmware for the Ultimate 2 all of its back buttons, rumble and Gyro is now detected in steam. The only thing stopping it from working fully is the steam input UI being updated to support it. You can technically mess with a layout on a different controller (like the steam deck controller) and export that as a template to configure gyro settings but that's less than ideal.
A Valve developer replied to note:
Yes, the UI support is planned but not ready to ship yet
Nice! Hopefully we'll see this expanded Steam Input support for more 8Bitdo hardware and other controllers in future.
When this lands, I might actually have to upgrade to the 8BitDo Ultimate 2.
Anyone knows if there is a third party config tool/driver that exposes the buttons like a normal controller /dev/js0 /dev/events?
... now if I could just find a controller about ten percent larger, my hands wouldn't ache as much. Playing games like Afterimage or Ori gets painful after a while.
So summarizing, you need the controller, a way to update it (probably you need windows for it) and a future version of steam.
Officially you need either Windows or a Mac with their more recent controllers, yeah. But this might help you run the upgrade tool in Wine if you don't mind a bit of tinkering:
https://gist.github.com/archeYR/d687de5e484ce7b45d6a94415a04f3dc
See more from me