Now, about the wifi part, why isn't there an Home Assistant extension that detects already room presence magically exploiting all of this??
There is with Zigbee:
https://github.com/orgs/home-assistant/discussions/960
But this relies on Hue. I would like something at HA level directly, aka a zero-effort solution if you already run a zigbee swarm either directly controlled by HA or via zigbee2mqtt