There is a PS2 beta from July 2003 floating around somewhere, but that has the near final product since it's only 3 months before release. There is a high likelihood a Gamecube prototype exists but there's no links or anything with it.
The most notable thing with the PS2 beta is this hellish intro cutscene .
Someone on the Donut team server told me about someone on this server That has discovered a SHAR dev-kit containing a GC prototype of the game. If this someone is really here, please answer.
After a lot of consideration on many factors over the past couple of weeks, the mod team have decided that the best course of action is to allow the custom save file to skip the Bart 1, Apu, Bart 2 and Homer 2 cutscenes. This save file is banned in No Mission Warps, with the goal to maintain the sta