What helped me a lot was getting an e-bike that I'm able to cruise around town at 20mph (32kph) in. I understand that this particular solution doesn't apply to you, since arthritis is triggered by joint movement, whereas my pain is triggered by impact on the damaged foot and ankle (and e-biking is low impact).
But this experience got me thinking a lot about small electric vehicles.
One could imagine a city center where most people walk or bike, and people with a medical permit could drive around in speed-limited, electric golf carts, which are fairly compatible with pedestrian-only areas. Perhaps the city itself would staff the golf carts with drivers who were summonable via app.
So people like us could drive to a parking garage on the outskirts of the city center, and then there would either be rentable golf carts at the garage, or golf carts able to be summoned to go into the city center.