I’ve been following the dlodlo progress. They are making it less bulky. It is 16mm (0.5") thick, weighs 78g (2.8 oz), 90FPS, 2560x1024 each eye, 10ms latency, small tether to either a smartphone sized VPU/GPU or a hook-to-computer version that does not require the portable unit.
The portable D-box VPU/GPU uses a PowerVR G6230 GPU. At 80-100GFLOP, it seems seriously anemic for HF style render graphics. GFXBench3.0 came out at 20FPS
So, direct tether to a computer seems to be what is required.
Rotational and positional tracking is performed with two 9-axis IMUs (gyro, accelerometer, magnetometer). The magnetometers would be used as the fixed reference to curtail accelerometer drift. With the Vive, the lighthouse beam sweep serves as the spatial reference. Using the ambient magnetic field for positional reference will work, though the question is how well will it work, hence a wait and see on this product.