Steam is a pretty inclusive platform, with support for a wide range of controllers, accessories, and peripherals, all with customizable controls that can be remapped in any fashion you want. One controller type that still isn't playable with on Steam, however, is Nintendo's Joy Cons, but that's soon set to change. Valve has announced that official Joy Con support is coming to Steam in the not too distant future.
This is already available in the new Steam beta, which rounds out the list of supported Nintendo and other older-system controllers, including those for the Switch Pro, NES, SNES, N64, and Mega Drive controllers. With the addition of Switch Joy Con support, Valve has made it possible to play with both at once, or with just one by itself, where it'll function like a simple standalone controller.
If you want to take part in the beta so you can get early access to this new feature, you can join it by going to Settings > Account > Change then next to Beta Participation, select you want to be part of the Steam Beta Update using the drop down. Wait for the download to complete, restart Steam, and you'll be in. Then you can start using your Joy Cons in a range of different games. They will work best in Nintendo's own titles, but there are plenty of controller-oriented games that could benefit from this unique style of controller.
What are some of the games that you'd like to play with Joy Cons?