Making the suggestion that a new Category Permission be added call Display. This will allow Admins to display the Category but prevent the topics from being seen.
A Use case for me is to display all Categories on the home pages for visitors but they can’t see the Topics. When they click on a Category, the Sign Up page is shown.
This new Permission could enhance the Gated Topics in Category theme component (https://meta.discourse.org/t/gated-topics-in-category/225454 by giving control at both the Topic and Category level. May have to change the Theme name to Gated Categories/Topics
Thank you Moin & Dan for responding and pointing me to the components. I will check them out. I expect they, along with Gated Topic Category, will work to accomplish the objective of restricting visibility & access to Categories/Topics.
I think it would be simpler and cleaner to have a new Display Category permission and link it to the Signup page like what happens when an anonymous visitor or logged out member clicks on Reply for a Topic within a Category that only has the See permission. This functionality would then be in the Core so no issues with components.