I think a killer app for this could be small screens. You could have a UI with pseudo-"buttons" around the edge of the screen large enough to see but too small

I think a killer app for this could be small screens. You could have a UI with pseudo-"buttons" around the edge of the screen large enough to see but too small to actually press, letting the interactions take place just off screen. This could let you turn a 2x2 inch screen like a watch into one that's effectively a couple inches larger in terms of the interactions available. Right now my watch's design is almost entirely constrained by having UI elements big enough to easily touch, taking up precious screen space.