Retro Controller Hub Plus for Nintendo Switch™ – Nyko Technologies
Old Skool Nintendo Switch/Wii U Controller Adapter - Gamecube
Ultimate GameCube Adapter by Panda Hardware — Kickstarter
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
This Nintendo Switch adapter turns your GameCube controllers wireless - The Verge
Nintendo Support: How to Use the GameCube Controller With Nintendo Switch
Unboxing Official GameCube Controller and Adapter for Switch! - YouTube
How to Use the GameCube Controller With Nintendo Switch | Support | Nintendo