From recent tweets (2021-08-07)

Stack-chan integrated with UnitV2 AI Camera by M5Stack
https://shop.m5stack.com/products/unitv2-ai-camera-gc2145
The camera recognizes human face and send face position to Stack-chan.
Then Stack-chan can follow the recognized face.

src: https://github.com/meganetaaan/stack-chan/blob/main/firmware/mods/face_tracker/mod.js