And it working even when your portable device isn't in the same wifi network ("Nearby devices" option) is pretty magical. Ultrasonic communication between phone

And it working even when your portable device isn't in the same wifi network ("Nearby devices" option) is pretty magical. Ultrasonic communication between phone and some-other-thing is stuff that you'd expect to read about being done in a lab, yet here it is in a consumer thing that's really cheap, and working flawlessly.