If anyone comes here curious as to how they can access Desktop, Documents, or Downloads, the answer is in the link above, for reference, but I’ll put it here in case that link expires.
In System Preferences -> Security & Privacy, select the Privacy tab.
From the list on the left, select Full Disk Access.
Click the padlock in the lower left of the window to unlock this setting, if necessary.
Click the + button to add Emacs to the list, then add Emacs.
Now in Emacs, do the following for each of the three directories: Desktop, Documents, and Downloads.
Press Cmd+O to open a file.
Open any arbitrary file in the folder you want access to.
From now on, you’ll be able to use C-x C-f to open ~/Desktop/, for example.
change emacs to emacs.bak
change emacs-x86_64-10_14 to emacs
Opening directory: Operation not permitted, /user/…/Documents
To help clarify (based upon my experiments – please verify) There seems to be three of these: ~/Documents , ~/Desktop , and ~/Downloads … I’m surprised ~/Downloads is in there because its not copied to iCloud.
The ns-open-file-using-panel must be done once for each of these. After that, it appears to work forever and ever. I even rebooted and it still worked. Go figure…