On August 5, PCGamer reported that the Steam Client Beta had been re-released and updated, allowing for official support of Nintendo Switch Joy-Con controllers. The Joy-Cons can be used individually as a mini-gamepad or in pairs with the Steam Deck. Improved support for Nintendo Online Classic controllers was also provided with the update.
Users must first access the Steam Client Beta and then click "Steam," "Settings," and "Account" to change the "Beta Participation" setting. Click "Steam Beta Update" from the dropdown menu and restart Steam to finish the installation.
Steam supports a wide range of controllers, both wired and wireless and including other Nintendo controllers. Unfortunately, there is no way to wire your Joy-Cons to your PC setup, so you'll have to use bluetooth for the connection.