What exactly is it? How does it work? The description says, “Imagine a world where a live 3D model of your own hand gives you instant feedback on your playing technique. That world may be closer than you think!” Just how close might this world actually be?
Also, in the Teemu Mantysaari Live 2018 interview, there is a demonstration of the hackmotion golf sensor, and @Troy also briefly mentions an arm band that measures emg muscle activity.
What all kind of technology is there like this, at the present time, for home use.