Hello,
I was able to get this running on retro handhelds, but without the beautiful webm videos. This is because the GMS version used with this game predates the modern video playback system (https://manual.gamemaker.io/beta/en/GameMaker_Language/GML_Reference/Drawing/Vid...), and GMLoader, the middleware, only reimplements modern video playback (see Deltarune). I was able to preserve the audio and subtitles, but for your awareness. :)
Thanks for your work with this game! Having fun with it so far!