Unless like Vision Pro there's a surroundings control that lets you go from total visibility outside the image to complete darkness — within the FOV — in any environment.

Edit: Since the FOV is only 70 degrees, that leaves 110 degrees outside the image, divided between the edges of the glasses and the rest of the room. So for sure in daylight outside light would destroy the theater effect.

Apparently there is a flap you can place on them to block out light.