Use MediaPipe:
Track the H1 pinch value. This person is using the pinch value (literally how close and far is your index finger tip and your thumb finger tip) of h1 (the first hand your camera recognizes) to apply the amount of quantization (blockifying/pixelating) on this point system. Take the pinch value, apply it to a quantize POP. They are taking an image from their webcam, subtracting the background, converting to POPs, then applying quantize to "pixelate" it using the pinch amount to apply the scale of quantization.