Pretty sure that already exists.
But it is mainly used for solving hardware problems where a technician can film whatever they are working on with their phone, and a remote technician can "draw" in AR on the image in real time to point towards the things that need manual interventions.
What about a camera that is covered by a cap that can only be lifted if they press the mechanical button on the side of the glasses?
You could still film things like posters to get more information about the event, while not filming everyone all the time.