My Jeep has a vertical windscreen. I have the Jeep branded hood deflector. When sprayed with a garden hose it helps deflect the flow, landing about half way up the windscreen.
What happens in actual driving is anybody's guess. The deflector is there to save the leading edge of the hood from flying branches.
I have quartz ceramic protection on most of my cars, that might protect from long term sand etching, but unlikely to help with stones as such.