Huh. Maybe could mod a lawn cutting robot to rake it?
That’s honestly a great idea, make it look like an air ball, lol.
I have piles of stones in yard now that never get raked and seem ok though
I don’t know your set up, but if the piles of stones are surrounded by nature, then there’s movement around it and they won’t look dusty and dead. Also, it looks different if it’s all rocks and there’s no contrast with at least equal amounts of nature. That could be it?