The issue comes down to how the device interacts with your computer. Just like the original version, the new Steam Controller has no native Windows drivers. This means the hardware relies entirely on the Steam app to function properly. If you do not have the game running via Valve’s storefront app, your shiny new gamepad turns into a useless piece of plastic.
Gamers Nexus also reported this and there are a lot of other news outlets also covering this. It is kinda the same as with the steam deck where I noticed that the inputs just don’t work until steam is launched. I really don’t like that I have to have Steam running for this controller to work. I don’t know if it is a dealbreaker for me, yet, but it really put a damper on my enthusiasm about it
It’ll have that on Linux like last time. You just need to set the uinput driver for the device. They had a generic gamepad one in the kernel for the OG. But not loaded by default as it’ll look like a kb&m out of the box unless you set a user-level driver config for the HIDs.
Valve were very supportive of Linux if people didn’t want to use Steam/Steam Input but other OS didn’t get their efforts beyond the Steam client.