And I just went to my test Mac, running OS 12. As far as I can tell, it doesn't have Full Disk Access (our App isn't listed in that dialog), and the App can use the "df" command.

Note that I just did some checking on my Mac OS 12 machine. Our app isn't in the list in the "Full Disk Access" dialog. Yet is able to run the df command. Does ANYONE know what security settings might block use of this command?