For comparison, the Nintendo Switch cardboard piano works by having you press a cardboard key with a highly reflective sticker on the other end, to lift that sticker above a barrier, so it can be seen by the game controller's integrated IR camera, which streams the image over to the switch over bluetooth, which then runs some image analysis to figure out which key sticker just became visible and THEN plays a note and the latency is STILL so much lower than on Android, that you can actually play it like a musical instrument.
The wiimote has built in IR blob extraction from the sensor on device, so I think he is wrong unless Switch/joycon changed things. In some modes, which piano may use, it basically is only sending sparse location data of 4 brightest detected light blobs.
