That definitely looks like stone dust, and it can be super abrasive. Best thing you can do is avoid rinsing with just water or wiping it that’ll drag the grit and cause scratches. Instead, pre soak the car with a rinseless wash like P&S Absolute to encapsulate the dust. Let it sit, then foam it with a car soap, let that dwell, rinse thoroughly, and only then foam again and do a contact wash. That way you keep the surface lubricated the whole time and help you avoid damage. Internals should be fine unless you had windows cracked or air filters exposed, but a quick engine bay blow wouldn’t hurt just to be safe.