On Big Sur (The platform where I test it), I never had to run chmod -777 for Vox Gremory, the executable should be preserved since I use tar and Unity 2021 builds for mac without issues even on Windows.
This is how it looks like during my tests: https://imgur.com/a/rxIJscT
Not sure what's causing the issue, my best guess is that something is preventing the game from being extracted properly or to be ran at all.
Viewing post in MAC Game immediately closes upon opening
It's probably me uploading on itch.io incorrectly, as I use Butler. My guess is that something happens to the archive during the uploading process which corrupts the executable within, similarly to what happens if I try to zip a Mac game on Windows. I'll be using tar format for packing in future, and hopefully that'll fix the issue.