Hey @mr-x ,
what @waffles is writing is nearly correct.
But please use the build from this topic, in the "FLASH" section:
https://forums.ubports.com/topic/5939/fairphone-3-3-fp3-fp3-port-halium-10
It makes the camera and audio module work on the FP3+, at least for stills (no video).
Good luck 🙂