It seems to work like this…
psmoveservice uses ps3 cameras to track psmove controllers to imitate htc vive controllers in steam..
freepiebridge can use a third psmove controller to provide hmd x/y/z position data to be COMBINED with phone yaw/pitch/roll.
also steamVR wont load properly unless it is selected as the sensor mode in trinus? could a steam+freepie option work?