https://www.theverge.com/circuitbreaker/2017/10/20/16507816/nintendo-wireless-usb-headphones-switch-update-firmware

Along with the ability to transfer save files and capture video, the Nintendo Switch’s 4.0 firmware update seems to have come with a hidden bonus: support for USB-based wireless headphones, via Engadget.

To take advantage of the new feature, simply plug in your headphone’s USB adapter to the USB port on the Switch’s dock, and you’ll be good to go. Enterprising Reddit users are also reporting that the feature works with the Switch undocked, assuming you’ve got a USB Type-A to USB-C adapter to plug your headphone’s dongle into the Switch console itself.