Valve is working to add support for the Nintendo Switch’s Joy-Con controllers in Steam. As part of the the newest Steam beta, Joy-Cons will be supported either individually or as a matched pair, similar to how you can use them either way for Switch games. If you want to try the feature out, you can opt into the Steam beta — Valve has helpful instructions on the Steam website — though fingers crossed that your Joy-Cons aren’t experiencing any drift.
Valve is also improving its support for Nintendo’s classic controllers it sells for Switch Online subscribers, though in the beta patch notes, the company didn’t specify exactly how. That feature was introduced to the public version of the Steam client just last week, letting you use the Switch-specific NES, SNES, N64, and Sega Genesis controllers on Steam.
And if you want to use a non-Nintendo controller with Steam, you’ve got some options there, too. Valve added support for Sony’s DualSense controller shortly after the PS5 was released in 2020 and expanded Steam’s support for Xbox controllers in early 2021.
Source: https://www.theverge.com/2022/8/5/23293916/nintendo-joy-cons-steam-valve-support