I… Dont know why this exists.
Ive been aware of a few ethernet projects for gamecube and none of them makes sense to me.
None of them use a custom chip/interface and require special code in software.
On top of that, none of them have merged the code into libogc (the open source gamecube homebrew library i help maintain ).
If i were to make a project like this, i’d use a mcu ( pi zero? ) together with a ethernet controller. The mcu would expose the same interface the official bba would, so even games could use it out of the box.

But hey, what do i know, right?