"Bluetooth wardriving" has promising google results, e.g. [1] [2] [3]. That would involve either driving around with such a setup, or planting a couple of them, depending on your coverage and update requirements.

1: http://mateslab.weebly.com/bluedriving.html

2: https://interruptlabs.ca/2021/10/15/Bluetooth-WarDriving-wit...

3: https://hackaday.com/2011/04/15/long-range-bluetooth-wardriv...