The PC recompilation project is reportedly the work of the Ganbare Goemon Discord member "Klorfmorf" and was built using the N64Recomp tool. This is a tool that was released back in May of this year and was also used to create the amazing The Legend of Zelda: Majora's Mask recompilation.
In case you need a bit of a refresher on what these recompilation projects are, they essentially allow fan creators to recompile native executables of the original N64 game on PC, while introducing various quality-of-life improvements that would be trickier to implement using traditional emulation methods. To get these up and running, players typically have to supply the original ROM, which is then used to extract the game's assets.
Unfortunately, right now, the Mystical Ninja Starring Goemon recompilation only works with the Japanese ROM of the game, but it's still well worth checking out if you're already familiar with the game.
Here's the download link (available via Google Drive).