Note that this isn't "Mac's sandbox system", it's TCC. That's an important distinction to make, because apps that have opted into the proper App Sandbox can't do this... they don't even have the ability to display a prompt for direct access to Documents/.

With the App Sandbox, sandbox extensions are issues whenever you open a file using the file picker. They only last until the app is restarted.

A caveat is that you can save "Security Scoped bookmarks" (basically a signed base64 blob [1]) and pass that around to preserve access, but that isn't very common.

[1] https://www.mothersruin.com/software/Archaeology/reverse/boo...