Similar problem with arthritis in the big thumb joints. I gave up a Kimber Solo semi-auto for a revolver that never needs to have the slide moved to load or clear. Recommend a S&W M&P340. light weight J-frame .357 Magnum. Not much fun at the range but its a great carry piece.
Had a long talk with my Gun Range instructor, a hammerless gun won’t solve my issues with the loss of fine motor skills. So I’m going to have to learn to shoot Left handed. It is my least used hand. At 69 going to be tough to relearn how to shoot with the hand that is not dominate.