That's a good question. I suppose it may be possible to use GPS data to estimate the phone's absolute heading. I just took a quick look at https://developer.mo

That's a good question. I suppose it may be possible to use GPS data to estimate the phone's absolute heading. I just took a quick look at https://developer.mozilla.org/en-US/docs/Web/API/Detecting_device_orientation https://developer.mozilla.org/en-US/docs/Web/API/Detecting_d..., and it seems to provide orientation, and not angular velocities. So it could also be that browser implementations fuse magnetometer and inertial sensors to produce the orientation estimate. Is there another gyro API?