I believe that just due to memory constraints, running any high-quality neural network on phones is currently impossible.

State of the art optical flow tracking needs about 10 GB of GPU memory to execute on full HD frames. I wouldn't know of any mainstream phone with that much RAM.

That, BTW, is also the reason why autonomous drones usually downsample the images before AI tracking, which has the nasty side effect of making thin branches, fences, telephone wires, etc. invisible.