Genghis, you said:
"...these aren't AoA devices in any way."
Beg to differ a little on this. Isn't JA describing the ADD sensor? Part of the pre-flight used to be a gentle twist to ensure that it was free to be servo'ed in flight.
ADD = Airstream Direction Detector.
Not AoA to be sure and full of local errors, but once calibrated for an airframe gave (gives) an indication of the angle between the airframe and the relative airflow. The indicator doesn't read degrees but "Units" and can be used for performance flying; typically approach and landing.