What is the bluetooth library for Adafruit CLUE? Does one exist to download?
Adafruit has circuitpython support for it: https://github.com/adafruit/Adafruit_CircuitPython_CLUE
The CLUE is just a bunch of sensors and an nRF52840. If you want to use it in an Arduino environment, I assume you can use the individual libraries for its components.