Unless you wanted to submit this to the Mac App Store, you could have just turned off sandboxing. With that off, the only permission required would be Catalina’s permission dialogs when any app first accesses various folders (Documents, etc.), and those are automatic without needing any code in the app to request them.
I thought I could locally, but it crashed on her machine which makes me think I did it wrong. I could have kept at it but I think one debugging session on her computer would have wiped out any time savings she would have realized.