I suspect those airliners which can fly at a specific AoA, have an AoA vane sensor on the side of the fuselage. No calculation required. So if I pull the stick all the way back, the computer will give me all it's got without stalling the plane. The AoA sensor has been a recommended item for all aircraft by the AAIB for years, even if it is just another channel on the FDR for the subsequent board of enquiry!
Sadly, I doubt we'll be seeing one of those in a cessna for a while (even a G1000 equipped cessna), so giving the pilot a good model of what affects AoA is as good as we can get. At least his eyes can take in what's on his 6-pack, and his brain can make a pretty good estimation of how to keep the aircraft flying. There's no Math involved if the mental model is a good one!