Want to use Bluetooth headphones on a FreeBSD system that has a 3.5mm audio socket?
You can with a Bluetooth transmitter! I'm using this model, after buying a different (cheaper) unit that had unacceptably poor quality.
https://www.amazon.com.au/gp/aw/d/B0CJY56XG3
Just plug it, switch to TX mode, and your Bluetooth headphones *should* auto-pair with it (how, I don't know ...)