Thanks for helping debug this issue.
I have been reverse engineering a Pure Sense fan for the past few months by inspecting packets in Wireshark on the communication between the Android App and the Fan. By this process I was able to find out the Mac address, Device Name etc.
nRF shows the device as "LE only", Advertising Type "Legacy", Complete Local Name: "Pure Sense".
I cannot see why the Puck would be any different.
Do you have any idea on how I can change my code to free up the serial (if that's what I need to do?) I'm not sure this is the right approach since other Bluetooth LE devices show up in the scan.
It's worth noting that the description the Puck shows for each Bluetooth device is different too, there are no friendly names shown for any devices.