You can use the Smash Brothers Gamecube adapter in portable mode with a USB C adapter (Rumble works too) : r/NintendoSwitch
Amazon.com: Mayflash GameCube Controller Adapter for Wii U, PC USB and Switch, 4 Port : Video Games
Power A's Switch and GameCube Controllers Make for Great Alternatives - Feature - Nintendo World Report
Cell Phone Rumble for the Gamecube Controller Orange - Etsy Finland
Amazon.com: Exlene Gamecube Controller Switch, Wireless Switch Pro Controller for Nintendo Switch/Lite/PC/Android/Ios/Steam, Support Wake Up, Motion, Adjustable Vibration, Turbo & Auto Turbo (Upgraded,Blue) : Video Games
Wired Nintendo GameCube NGC Rumble Controller Gamepad GC Wii U Switch Console | eBay
Upgraded Exlene Gamecube Nintendo Switch Controller Gamepad Joystick for NS/Lite/Windows/IOS, Wakeup, Rumble, motion, NFC| | - AliExpress
raphnet. - N64 controller to Wii/Gamecube adapter (v2)
PowerA GameCube Style Wired Controller for Nintendo Switch - Black - Walmart.com
raphnet. - N64/Gamecube to USB adapter with vibration/rumble support
raphnet. - N64/Gamecube to USB adapter with vibration/rumble support
Amazon.com: GameCube Controller Adapter : Video Games
Best Nintendo Switch GameCube Controller Adapters | Digital Trends
It's technically possible to play Ultimate with GameCube controllers (and rumble) in handheld mode. : r/smashbros
Gamecube Controller Adapter for Nintendo Switch | Hand Held Legend
Nintendo GameCube Wii 6' RED OG Rumble Controller Pad Teknogame New (Gamepad) 722267833695 | eBay
Amazon.com: EXLENE Gamecube Controller Switch, Wireless Switch Pro Controller for Nintendo Switch/Lite/PC/Android/iOS/Steam, Support Wake Up, Motion, Adjustable Rumble, Turbo & Auto Turbo (Upgraded, Black) : Video Games
How to use Rumble on Dolphin with Mayflash 4-port Adapter. - YouTube
Dolphin Emulator - Dolphin Progress Report: November 2015
Best Nintendo Switch GameCube Controller Adapters | Digital Trends
Nintendo Switch v4.0.0 Update Brought Surprise GameCube Controller Adapter Support | Nintendo Life
