The situation, unless something has changed, is that the 15v3 has all the hardware necessary for Bluetooth, but doesn’t ship with drivers because FOSS drivers don’t exist yet.
in order to help fix this problem, Purism is, last i checked, trying to hire a developer to make these drivers.
If you want Bluetooth and don’t care about the drivers being trustworthy and open, you can just install proprietary binary drivers. I’m not sure which, someone will chime in.