Just a simple check-box or switch from within the Glide Dashboard-Editor that when selected turns all screens and tabs within the accessible version of the app invisible and a message that says something like “We are doing some work on the app and will return shortly”… ideally a custom message.
This wouldn’t affect the editor dashboard for the app, and would therefore allow you to do major upgrades to your own app without any of your users using the app while you’re doing that sensitive work.
As of right now, I’m not sure how to do larger upgrades to my app and be sure that users wouldn’t see the changes in real time and perhaps experience broken functionality during that time. The only thing I can think of is making a copy of the app and doing the upgrades there. Then when finished, downgrade from Pro on the former version and upgrade to Pro on the upgraded version. But that would require every user to delete their former version and go through the entire process of adding the new version, signing in again with pin, etc.