Can you imagine other use cases than projection?
yes
vtubers
human interface device for quadriplegics
automated camera tracking/zoom for video calls
emotion recognition support software for people with difficulty reading or understanding emotions (ASD)
truly smart, smart home that can track and respond to gaze, e.g. "can you turn off that light" and it will turn off the light they're looking at
sleep detection for smart locks
liveness detection for identify verification systems
vr tracking for interactions that both escape the uncanny valley, and feel more real time
need more?
are there others?