Interesting DIY project! It reminds me of a startup called OccuSpace (https://occuspace.io/), which offers a similar occupancy solution but as a service. They may be leveraging similar technologies to provide real-time occupancy data, which is incredibly useful for managing space in offices, public venues, etc. It's a good example of how these concepts are scaling up commercially.

I wonder How well can your DIY sensor or OccuSpace figure out what kind of devices are in the room or who's using them. Can they tell different users or gadgets apart?