I have dysautonomia, but not POTS. I had the tilt table test, and it was inconclusive. I’ve struggled with the nerve condition for 10 years. I also have kidney disease and hypertension. Some tasks that would be useful for me from a service dog are emergency medication retrieval, counterbalance, picking things up and handing them to me (so I don’t get lightheaded from bending over), and guiding me to safety when I lose my vision due to a migraine. I also had hope that a service dog could alert me if my blood pressure gets too high so I can take emergency medication before it gets too bad, but that likely wouldn’t apply to you.