Valve sent over a press announcement to highlight that the Steam Input API has expanded its support of the brand new PS5 DualSense Controller.
This has been ongoing work since earlier in November, with multiple Steam Client Beta updates expanding the Steam Input API. Starting off initially with just supporting basic input. However, across other Beta updates on November 18 / 19 and 20 they've now added in support for:
- Rumble + Rumble over Bluetooth
- Gyro functionality
- Allowing external audio based haptics while rumble is enabled
With all this hooked up, Valve say that now all games that support the Steam Input API "are now fully compatible with the new PS5 controller - with no developer updates required, it just works".
You still need to be opted into the Steam Beta Client, with full support rolling out for the PS5 DualSense Controller into the stable client after further testing has been done.
As for how it works on Linux, you're going to need some updated udev rules to work fully. Valve contractor Timothee Besset mentioned on Twitter they've put out an update to the Steam Installer, and you can also find the full udev rules on Valve's steam-devices GitHub.