For the most part, a phone gets you most of the way there. They're currently the apex predators of the mobile space.

I think the one thing that a headset does bring to the table is the hands free nature of it. There are quite a few AR apps and use cases that phones can currently do that fall short because you need to hold your phone out and that's really invasive and fatiguing.

In theory you could have things like a walk through of a DIY engine repair that adds virtual pointers and highlights to important things.

You could do this in a video where you go to your phone, watch a step, rewind, put the phone down, find where in the real world the thing is, do the thing, wipe your hands, pick up the phone, repeat etc. but I imagine it would be nicer in AR.

I'm not saying spend a trillion dollars on this, just that it would be a neat thing.