This AirPods case wasn't made to be babied. It was made to be used. It'll get marked, it'll pick up the rhythm of your pocket, bag, and daily carry, it'll develop a patina that's yours alone.
That's not wear. That's what real leather does.
If something spills on it, wipe it with a dry cloth and let it air dry — away from the sun. Avoid soap, ink, and alcohol. That's it. The rest takes care of itself.