Device Tracking

https://www.home-assistant.io/components/device_tracker/

Bluetooth

https://www.home-assistant.io/components/device_tracker.bluetooth_tracker/

device_tracker:
  # Bluetooth
  - platform: bluetooth_tracker
    interval_seconds: 30

To improve first detection, scan Bluetooth devices with the phone while HA is restarting.
Sadly, you can’t combine multiple MAC adresses on one device in HA. So a _group must be created to handle multiple tracking._