Not sure what I think of a tablet "coloring book" but the tech is intriguing... According to https://cococolor.com/pages/instruction#best-results https://coco

Not sure what I think of a tablet "coloring book" but the tech is intriguing... According to https://cococolor.com/pages/instruction#best-results https://cococolor.com/pages/instruction#best-results it seems the apps just listen in on the mic and the stylus emits some sort of (ultra?) sound/sequence of audio pulses for each of the 4 buttons. Anyone know if that's correct? If so, I wonder what the frequency is... are all Android devices responsive to these sub/ultra sonics?