8Bitdo GBros (Wireless Switch Adapter for Gamecube Controller) - us.MaxGaming.com
Amazon.com: Gamecube Adapter for Nintendo Switch Gamecube Controller Adapter and WII U and PC, Super Smash Bros Gamecube Controller Adapter. Support Turbo and Vibration Features with 180cm Long Cable : Video Games
Nintendo Support: How to Connect Additional GameCube Controllers to Nintendo Switch