PID vs Open Loop

just finished the boost control course and had a question about PID in general...

I guess the main benefit of PID is that, if tuned correctly, you don’t have to rely on or tune various factors such as EGT, IAT,ambient, etc and simply rely on the algorithm and its input

in some of the videos though, I understood (possibly incorrectly) that you can still overlay corrections from different sensors while using PID. Is this right?

If that’s the case, why bother? Isn’t the point of PID that you shouldn’t have to? I suppose that overlaying this just gives better base input and therefore PID doesn’t have to correct as much and likely more accurate?

also, why couldn’t you tune ignition and fuel with PID? I guess fuel is already when in closed loop lambda, but does anyone use permanently closed loop lambda PID?

I guess ignition is harder since I can’t think of a way to measure torque on the road...

PID control helps you reach (and stay on) a target, the corrections will move the target.

Thanks, that makes more sense now