Duplicate: How to share only a specific prototype to view-prototype-only users?

No, it’s not possible unfortunately. You can duplicate the page and keep working there, then when the work is done remove the current page and move the new duplicate page contents there (right click → move to page) so the prototype links don’t get lost. Or simply change the prototype link you give to the client.

I thought as much, but thanks for confirming. My only issuing with duplicating pages is how to handle components. Sometimes I have a separate page for components, so I’d need to duplicate that page too to avoid things unexpectedly changing.