You're right, my nomenclature may have been wrong, swapping wastegate for blowoffThis is not at all how a wastegate functions. At idle and low boost, the wastegate is always shut. Once you hit your wastegate spring pressure (or electronic boost threshold in the case of the Raptor with an electric wastegate), then the wastegate opens in order to control boost at higher loads and rpm’s in order to avoid overboosting or boost creep. When the motor is in vacuum, and boost pressure less than 10psi, the wastegate will be closed. Not sure what pressure it opens on this truck but I would assume somewhere in the neighborhood of 1 atm (14.7psi) or a little less. At peak boost the wastegate will be fully open.
OP, your operation sounds normal most likely. Put it in sport mode and go WOT going up a slight incline, letting it rev out. If you don’t see higher boost under that condition, something is wrong.