8BitDo has just released a wireless controller adapter for the Switch and Windows PCs. The GBros. Wireless Adapter for Switch allows gamers to connect Gamecube controllers, NES and SNES Classic controllers, and the Wii Classic controller to either the Nintendo Switch or a Windows device (running compatible software) wirelessly.
https://www.notebookcheck.net/New-adapter-from-8BitDo-wirelessly-connects-a-Gamecube-controller-to-the-Switch-and-Windows-PCs.357756.0.html