Ah, it's simpler than I thought.
Could you try exporting via the "Windows, Mac, Linux for Markets" option? That should result in the appropriate file structure for this to work.
Turns out there was one last issue:
https://github.com/renpy/renpy/issues/1326
It seems that by default, there's an issue with how macOS deals with file attributes. I followed the terminal command to clear the folder attribute for it to launch, otherwise it crashes upon launch.
If you're able to do that before distribution, that should help with this last problem. Otherwise I can provide a zip with my modifications so that you can distribute that version.