Woah, thanks for all the info man. Proper play tester stuff. Glad it worked in the end :)
i hope it doesn't upset you, but while making the tests, I downloaded the Windows version of your game and replaced the JS files with ones called by the version hosted on itch (on this frame). By running a simple webserver on a localhost, it's possible to play it on any operative system. So, it's technically possible to make an offline Linux and Mac version, but I'm not sure if mounting it would be foolproof and worth supporting.