ESP32 are small, low cost Bluetooth/WiFi boards that can be programmed using Arduino IDE. Shogunxam has a project, ESP32 BLETracker that detects Bluetooth LE devices and sends the information to a MQTT server.
The software provides a web interface that allows setting of the devices to be tracked, the scan period, MQTT parameters and viewing of the logs.
There’s a growing number of operating systems for microcontrollers on single board computers, most of which can scan for Bluetooth LE devices such as beacons and connect to them via GATT for setup and extraction of data. Zerynth is now one such OS that you can program using Python. Zerynth r2.2.0 update allows use of Bluetooth LE.