The fine folks over at NeoGAF and Reddit have discovered that with the new Nintendo Switch 4.0.0 system update you can now use USB headsets. This includes wireless ones that use a USB dongle. You simply plug in your USB wireless adapter into one of the USB ports on the Nintendo Switch Dock and then the system will recognize your headset. By holding down the HOME button you can adjust the volume of the USB device.
I tried this out with my PS4 Gold headset and it worked great. This is a very nice feature for those who want to play their Switch on the TV and and still hear the game sound through a headset. Some have discovered that you can get this to work in portable mode if you have a USB to USB-C adapter hooked into the USB-C port on the Switch itself.
Nintendo didn’t list this feature in their official documentation, which probably means it’s not compatible with all headsets. Reading through some posts on NeoGAF it appears some people are having issues with it working, but if you have a wireless USB headset it’s worth a try!