Is there anything I can do so that only the main url is displayed in the browser bar for particular pages/posts?
I don’t want the user to see the urls of certian password protected pages when they are on them.
If that’s not possible, is it possible just to have the main url displayed for all pages/posts? If so how, is this something I would do with a GeneratePress setting?
not something the theme has any control over.
You would need to look into URL Masking which would be done a server level or some form of URL redirection. But unfortunately it’s out of our scope.