How to get bluetooth headset working
I have Trisquel 11 on my laptop, with pulseaudio-module-bluetooth and a bluez gui installed. I am using XFCE as a desktop, the system is netinstalled so some packages may be missing.
The headset shows as a serial device, I expect that there are two profiles: music and speech.
If the GUI isn't working properly, try with bluetoothctl (https://www.makeuseof.com/manage-bluetooth-linux-with-bluetoothctl/). Once you've paired the device, it should appear in the GUI and you can manage it there. If there's an issue with pairing, you should get more information from bluetoothctl. Are there any errors in the system logs?