Steam will support the Nintendo Switch Pro Controller beginning with a Steam Client Beta update that released on Wednesday.
The client makes the Pro Controller fully bindable and customizable, including such features as its gyroscope and vibration. Settings are changed through Controller Settings page, which is the same page that configures PlayStation 4 and Xbox One controller support.
Notably, this page includes a the global option to “Use Nintendo Button Layout” which can be used to swap the A/B and X/Y buttons of a loaded configuration, which will be useful for those who choose a template configuration for Steam Controller or Xbox One. Community configuration sets, shared over Steam, are also available to those using the Switch Pro Controller.
Bear in mind, the Nintendo Switch Pro Controller does not have analog triggers, and this won’t give it to one either. So it may not be the best option for games that have a throttle or other similar command on those buttons. Otherwise, the support is a way to extend some value out of the $69.99 gamepad.
Valve has full instructions on how to configure the support, but remember you need to have opted into the Steam Client Beta first. Users on Reddit have some additional details on how it works — such as controlling the LED light on the home button.