It's a huge technological problem to solve, and I doubt it will be solved by a third party, rather than Oculus/Google. Positional tracking relies on external de

It's a huge technological problem to solve, and I doubt it will be solved by a third party, rather than Oculus/Google. Positional tracking relies on external devices at the moment - Infrared Constellation Tracking with the Rift, and Lighthouse tracking with the Vive (and other SteamVR based devices). Without an external tracking device to rectify motion against, using gyros/accelerometers is only enough to reliably get 3DOF. A potential halfway solution would be to use some impressive CV techniques on the phone camera to track hands, but only where you're looking - mix that with the tilt data of the controllers - and some inverse kinematics. The more signals, the better the tracking.