Yes, I understand. I have a similar situation (which is why I created that feature request).
I guess my point is that if files are stored in GDrive and not public, then when an app user follows a link to a file, then they’ll be asked to authenticate (regardless of the fact they may already be logged into the app with their Google Account). And I don’t believe there will be any way to show the contents of the files in the app.
Getting back to your earlier question…
If the files are being uploaded to a table that’s linked to a Google Sheet, then it’s easy enough.
Glide will store the links to the files, and these links will show up in the Google Sheet. So all you need to do is fetch the files via those links, store them in GDrive, and then replace the links in the Google Sheet. You could automate this with some Apps Script, or an automation tool such as Integromat.
Once the original links have been replaced and are no longer referenced in your app, the files will be purged from Glide storage. I’m not 100% sure, but I think this happens within 30 days.