Hi Lyman;
Yes, that's what I'd figured was in mind as I know AoA can't be derived from any other flight or system parameters.
I do think that someone "tuned in" to his/her airplane could make use of this information so in that sense it's another tool, subtle and not widely nor well-understood even in the instructing world, (in fact I know an airline that refused to authorize use of the FPV/FD and would not train or permit its use in operations).
I think had they had the FPV they would have seen this, (quickly...time yourselves... 3, 5, 10 seconds with noise, buffeting, warnings and fright, what's the AoA? What angle are we going down at? Should I pull or push?):
