TMac
My wife's SUV is an explorer ST and it has a juice box... So me saying no cels is a valid statement.
If they're electronic wastegates it's possible to control them with a piggyback
Same with oxygen sensors, it's a 0-5v volt scale if you tell the car is leaner then it really it is, it adds fuel.
You said your engineer I am also an engineer I'm an information security engineer and Ham operator and I do all kinds of electronic experimentation for fun. So the two of us should be able to discuss how a piggyback works with a common ground unless you just don't understand electronic engineering which is okay I don't know what type of engineer you are.
I don't have my laptop with me so I can't open up the map on an HP tuners and see if the voltage to AFR scales in there for this platform but if it is you could also open it take a look and understand that let's say x voltage is on a wire and that equals 11.2 AFR. If you tell the car that it's really out of 10 8 instead it's going pull board fuel out to attempt to reach 11.2.
This is the core of how piggy backs work!
Of you wanna learn more , Take a moment read Jeff Hartman's book how to tune on a modify engine management systems, and it will make way more sense.
I only came here to give info since folks asked. So chill out man.