I've never actually thought about this until now, when you calibrate a smart trainer, where is the information stored?

In the past, I've used the calibration in the TrainerRoad app and then done my workout on TrainerRoad. Now that Garmin has smart trainer control I'm going to cancel my TrainerRoad subscription and just do workouts through my 945. However, I can't find any calibration option in my Garmin. This leads me to believe that I can use my Wahoo phone app and it stores the calibration on the smart trainer. Does anyone know how this actually works?