Support for Nintendo's classic controllers is included in the latest update. The change in Valve's patch notes means thatSteam now supports the Switch-specific controllers.
If you're a Nintendo Switch Online subscriber, you'll only be able to purchase the controllers if you do. The N64 and Genesis controllers are out of stock, but you can get the NES and SNES controllers. When they are available again, you will want to jump on them quickly because Nintendo doesn't say when they'll be back.
Qanba, Dragon Arcade, and Hori's Fighting Stick Mini 4 are joysticks that can be used in fighting games. You will be able to see a firmware update dialog on Windows if you have an official dualsense app for PC.
It was confirmed by Valve that Nintendo controllers are supported.