You can already get kidney stones pulverized. They basically put you in a special bathtub then use ultrasonic waves to blast the stones into pieces. The waves pass harmlessly through the water and your soft tissue, but the stones basically shake themselves apart because they’re too hard to flex with the waves.
Given, you’re still pissing jagged sand afterwards. But that’s better than pissing a jagged pebble. Most of the pain from kidney stones comes from the ureter stretching around the stone, so pulverizing it helps mitigate a LOT of the pain.