Open source doorbell camera software running on Raspberry Pi Zero. Face recognition and motion detection already built-in, so I've set it up so that I get a message on element when someone is at the door and a video of any motion longer than 5 seconds. Not fully optimized yet.
I can't without doxxing myself sadly. The image vision detection is built into the SoC, no clue about the underlying library but it is programmable to a degree, so I assume it must be OpenCV