Is it possible that in this discussion (and manuals #1), the differing opinions represent different viewpoints.
First, theoretical, with streamlines, upwash, etc, which could indicate different AoA with configuration, as measured at or around the airfoil shape. Where is the AoA sensor (human viewpoint) located?
Second, a practical view; with this, AoA as measured by a vane or other sensor to provide a displayed value which may be calibrated in units vice true angle. In commercial aviation the raw AoA angle is probably adjusted with aircraft configuration so that the ‘stall AoA’ (a unit value) is given at the point of stall for all wing configurations, thus the indicated stall ‘angle’ appears to remain the same. And as discussed, this may not represent what the airflow is doing over the wing, particularly as sensors for stick shake/push and minimum airspeed alerting can be fuselage mounted.
A further confusing aspect may come from the pictures @#1, which appears to show an AoA display for a light aviation aircraft. I doubt that the display format would meet and commercial certification regulation.
Whilst the display might be marketed as indicating ‘true’ AoA, the format may only represent the inability or cost in adjusting the raw value to provide a more risk free interpretation and practical use.
Also in these light aircraft, what form of AoA sensor is used. Many years ago I recall a leading edge, mini-vane sensor which I understood detected the airflow stagnation point at the stall angle - relating AoA to streamlines, etc.