An in-progress decompilation project started on September 9, 2023. The GitHub page for the project can be found here.
Currently supports all three retail versions of the game on GameCube: JPN (GZLJ01), USA (GZLE01), and PAL (GZLP01), which all come with full symbol maps on the disk. The Wii U HD remaster is not supported.
Although no debug build of the game has been found, the Japanese kiosk demo had symbol maps for the debug build left on the desk, which reveal the names of all inlines, except for those that were added in between the demo's release and the retail game's release.
The game shares a large amount of engine code with Twilight Princess, a game which does have a known debug build, so referencing that game can sometimes help in decompiling this one.