At least FFB for my basic saitek gamepad works out of the box in proton games and even in some emulators like dolphin. Haven't had steering wheels or pedals but always wanted. They are surely a different beast to reverse engineer. I have no doubt racing gear manufacturers will increasingly take care of linux compatibility with the momentum in linux gaming. And then there are all these OSS wizards already working on the most exotic HW. SteamDeck I don't know. I don't see that many linux steamers sadly.

I'm a bit of a reverse engineer myself (insert william dafoe meme) and had a successful pull request for controlling rgb lighting on my headset. Nothing compared to steering wheels or the like but I never did reverse engineering before and knew just a little C and it worked and was fun. Thing was I needed Windows to monitor the USB data when switching stuff in the OEM software.