Jmar,
Ok my left arm was like that when I was little, but I did squeeze a ball over the years ,gave me a grasp enough to reach a semi steering wheel between shifts for 25 years. Maybe trying to squeezing a rubber ball,may help, for rest use the arm of the chair to support your arm it help me driving for hours, took the weight off hanging the arm does. This is old school for sure but it did help me, will it work for you?
Best Wishes,
Tom