[b3lvedere]

This is mentioned in the article:

"What About the GameCube Broadband Adapter?

Yes, the GameCube had an official Broadband Adapter (BBA). But Animal Crossing shipped without networking primitives, sockets, or any game-layer protocol to use it. Using the BBA here would have required building a tiny networking stack and patching the game to call it. That means: hooking engine callsites, scheduling async I/O, and handling retries/timeouts, all inside a codebase that never expected the network to exist."

[brookman64k]

I didn't finish reading the article before commenting. Mea culpa! Maybe it would be possible to use Phantasy Star Online's network stack via the streaming exploit. But that would leave the hooking part.

[LeoPanthera]

I wonder if you can bitbang an ethernet interface to abuse it into being a serial port.

[mrheosuper]

At that point why not bit bang any spare GPIO ? like GPIO for 2nd player controller ?