I can see so many different points of view here.
In my model the customer gets a link to a Pro app that I have created. They use the app with no concept of Glide or any other services being used behind the scenes (e.g. Integromat or Zapier).
From time to time they will request a new feature (maybe chargeable) or find a bug (rarely, clearly …). I then need to work on the app to essentially create a new version, so I very much share @Deena pain in this respect. It is a nightmare trying to hide stuff while you work on it, let alone perform testing.
However for me, I would prefer the more traditional “staging” or “draft” environment for dev and QA which could then be “made live”. I think that offers the best blend of flexibility and ease of use.
I’m not saying this is easy to do, however I think it’s essential when you are building apps with any level of complexity for customers with demanding requirements. Glide fits the bill in terms of creating the apps, no question, but is not there yet in terms of maintaining them.