How would an "angle of attack" sensor compare to a stall sensor used on full scale aircraft?

I get how the stall sensor in light planes (full scale) are built into the leading edges and do their thing, but the pictures of the sensor on the failed 737 Max look like they are just hanging a small flag on the outside of the fuse and measure the angle it's running at compared to the fuse. Air flowing over the "flag" will keep the flag parallel to air flow no matter the angle of the fuse. It's up front to keep it in fairly clean uninterrupted air.

The flag is going to stay parallel with the airflow going over it, so they simply have to compare the difference between the angles of the flag and the fuse to get their info - which would really be angle of attack, no? They can then use the angle of attack and airspeed to safely predict stall conditions - assuming the angle sensor(s) aren't frozen up, and the software is working correctly.

So, to bring this into the RC world, angle of attack sensor could be a small flag mounted on a sensor that would measure the angle the flag was running at as compared to the fuse. Could work something like a gas gauge where the float has been replaced by a flag running on the outside of the fuse? -Al