I had great result resurfacing worn leather cover on a steering wheel with Angelus Direct leather paint. It goes on with an inexpensive artist brush, in 4-5 thin layers, then you seal it with a matte finish and no way you will tell it from the original leather dye.
Originally it is intended to be used on leather shoes, and I tried it on old worn leather shoes I liked for great fit, but dye was worn completely. They held up for a year, so I bet it is quite durable, so getting a “new old car” in with damaged leather steering wheel cover I decided to give a try. So far - quite good.
They have instructions on their site.