So Nintendont was updated to support the GC adapter for Wii U

GameCube Broadband Adapter (BBA) support is now implemented in Nintendont. You can use either a USB LAN adapter or your Wi-Fi. : r/WiiHacks

New 2020] How to use Official GC adapter on GC Emulator for WiiU! (nintendon't)

pdobq Gamecube Controller Adapter for Nintendo Switch / WII U / PC. Super Smash Bros Switch Gamecube Adapter. 4 in 1 Plug and Play Game Cube Adapter : Video Games

Connect upto 4 classic gamecube controllers to a Wii U or PC USB or switch Game with the classic gamecube controllers

GameCube Controller Adapter for Wii U, PC USB & Switch - NEXiLUX

Gamecube control adapter : r/wii

Nintendont and my wavebird aren't working on my Wii U and need help

GC Controller Adapter for Wii/Wii U ( Edition) for Nintendo Wii, Wii U

4 Port GameCube Controller Adapter for Nintendo Switch Wii U PC Super Smash Bros

GameCube Controller Adapter for Wii U, Nintendo Switch and PC USB by L

GameCube Adapter doesn't work with Nintendont. : r/WiiUHacks

GameCube Controller Adapter Unboxing - Support Wii U, Nintendo Switch

pdobq Gamecube Controller Adapter for Nintendo Switch / WII U / PC. Super Smash Bros Switch Gamecube Adapter. 4 in 1 Plug and Play Game Cube Adapter : Video Games

Can you use the gamecube adapter for wii games that support gc, like mario kart wii? : r/wiiu