Do not know the precise details of how the audio vario works, but the
idea is an audio tone is generated based on how fast air is moving
into/out of a fixed chamber.

Could you not take an audio vario, delete the chamber, and plumb the
vario to a "stall horn" type device?

The idea I have, is the vario makes no noise on the sitting on the
ground, but does make noise when exposed to airflow (specifically,
changing airflow due to climbing/descending). Same thing with a
"stall horn"....makes noise only when exposed to airflow.

Perhaps all we need to do is add a "T" fitting, some more tubing, and
a selection valve to our current audio vario. Plumb the new tubing to
a pitot bent at the tip to start picking up airflow if the plane
pitches up to the stall angle (rest of the time, the pitot would be
"flat" to the airflow and just measuring static pressure).

If this works, then all you have to do prior to landing, is switch the
vario's input from the normal TE probe to the new "angled pitot" AOA
probe. If you start hearing audio tone from the vario, lower the nose
to reduce AOA.

Anybody have comments on if this would work?

John