Another fresh Steam Client Beta went up on November 13, improving support of Steam's own Steam Input handling with the newer controllers from the next generation consoles.
The Beta notes that the PlayStation 5 DualSense controller now has initial support with Steam, however there's a few advanced features (trackpad / gyro) that are not currently supported. Additionally, the Xbox Series X controller should no longer show up as 2 separate controllers.
Nice to see Valve getting in early on that. They're not the only ones doing so either, as SDL 2 the cross-platform development library designed to provide low level access to audio, keyboard, mouse, joystick, and graphics hardware also recently added in support for both the PlayStation 5 DualSense (commit) and Xbox Series X too (commit). Both of which were added in by Sam Lantinga from Valve.
Additionally, if you were seeing lots of blank windows when starting Steam on Linux that should now be fixed.
To try out the Steam Client Beta at any time, you can opt in / out by going Steam -> Settings and then see this: