It worked on my Android tablet but I can't scribble a note and draw a picture/diagram with the stylus. I don't know anything about iPads but on Android you have the USI pen and for any app that understands the USI pen, it interprets fingers and stylus individually, the stylus is active so the tablet knows when it is input from the stylus or input from a finger. The google Cursive app which is the standard Android note app shows this well, stylus only writes and fingers only pan/scroll/zoom unless you switch it into finger mode so you can write with a finger.

If you managed to give all the features of Googles Cursive app within your Poincaré disk paradigm, I would happily drop $100 on it, assuming it worked as an offline app.

Edit: should mention that I don't think this is worth $100, other than to the handful of people like me who it would be perfect for assuming it was well executed. You would probably make more charging far less. The paradigm could translate amazingly well to the tablet/stylus experience if the details are worked out well.