The point of the very large 62 degree flap angle was to enable the wing to deliver meaningful lift at low IAS during the transition to from the hover. Numbers above are correct so you would only start to “fall off” the wing into purely jet borne flight below about 30kts. That meant that until that point you didn’t need so much jet thrust which in turn meant saving the time limited engine ratings at higher JPTs or limited volume of water injection available until you really needed it in the hover.
Once in the hover the 7/9 had a range of lift improvement devices like the strakes, front LIDS door and rear gear door to help entrain airflow close to the ground and cushion ROD.
When considering the Harrier nozzles also remember that true 90 to the ground was not 90 to the airframe deck angle so the hover was around 82 degrees nozzle for a vertical thrust vector.