The small amount of experience I have with playing around with raw hardware inputs on Linux makes me kinda surprised it took this long and guess that it was to polish this and that someone had a more or less functional version shortly after they decided to try.

I forget the name of the system, but they have a rules system that can be set up to do arbitrary actions based on arbitrary hardware messages, without even needing to do any kind of binary driver at all.

I used it to disable the volume commands from my soundbar while trying to get it to behave like it did with the optical input (where soundbar and PC each have their own independent volume settings), because when connected via USB, it would send the volume changes to the PC, so it looked like adjusting the volume changed it in both places. Turns out when in USB mode, it doesn't use the soundbar volume for anything and the "double effect" was just an illusion caused by the PC steps being larger than the soundbar ones. It was nice having a system to actually check this.