I am trying to imagine how an AR/VR single device could work. Microsoft has shown Hololen, which works with many different accessories. I think the ideal device would have one single small controller. Something like the Airpod charger but with a touchpad similar to the AppleTV remote would be great for this.The user could even use it in their pocket to control the UI and swipe, double tap, etc...
One app that would be nice is a zoom app, which uses cameras to zoom on an object and track it.
To switch between AR/VR, there could be a touch sensitive surface on the device : swipe to the front to switch to VR, swipe to the back to switch to AR.
Do you have any cool ideas for AR/VR that don't exist yet?