Valve’s latest release of the Steam Client Beta has made some changes to Steam Input, which now includes support for the Nintendo Switch Joy-Con controllers! Previously in 2018, Valve added support for the Pro Controller, and in 2022, has decided to give the same treatment to the Joy-Con.
Additionally, the update also improves “support for the Nintendo [Switch] Online classic controllers.”
Full beta release notes:
The Steam Client Beta has been updated with the following changes:
– Added support for Nintendo Joy-Con controllers, both individually as a mini-gamepad and combined into pairs
– Improved support for the Nintendo Online classic controllers
[Source: Steam Community]