I broke my best fingernai/fingerprintl/wrinkle brush, and the other one has bristles on both sides, one side stiffer than the other. After a while, it's not comfortable to rake the stiff bristles over my tender fingers.
But I had this old car washing brush. They probably still sell them. It's shaped like a rowboat, rounded at the front but coming to a point. Flat at the back. This one is red with whilte bristles.
I guess it's meant to not scratch the car's paint -- Are you really allowed to use a brush on the paint? -- but it works well on my hands, even without soap, getting all the oil etc. of my fingerprintes and the wrinkles on the top of my knuckles. And it's much bigger too, so it goes faster. It works even better than the broken briush did.