These controllers were all working on SteamOS before as far as I know, so I’m interested to see what this changes. My understanding is that previously their controllers just show up as generic xbox controllers, and now they will be properly recognized. We’ll see if this has any other benefits like custom bindings for back buttons and things like that.
It sounds like back paddles will be treated as separate inputs, I found where some people got to try out beta firmware for some of the 8bitdo controllers some months back, and that was specifically mentioned as some of the new functionality.