Almost all smart glasses (Ray-Ban Meta, Alexa Echo Frames) rely heavily on voice. It is hands-free and socially acceptable in many contexts, but privacy remains a concern in crowded spaces.
Located on the temple arm (Swipe to Volume). Reliable, but limited in gestures (Tap, Double Tap, Swipe).
The holy grail of AR (Snapchat Spectacles 5, Meta Orion). Cameras track your hands, allowing you to pinch and grab virtual objects. Currently power-hungry and mostly found in developer units.