There is a project community driven by @andrewjfreyer which seems to be interesting https://github.com/andrewjfreyer/monitor
with the App from @Odianosen25 Home (Monitor) Presence App V2
It requires to install Raspberry PI Zero W as a monitor device.
On the BT beacon side an integration with owntracks seems to be a simple solution https://www.home-assistant.io/blog/2016/04/30/ibeacons-part-1-making-presence-detection-work-better/#tips