I think there will be plenty of contrast between white shaker cabinets and a charcoal gray island. We’re about to do a complete redo of our kitchen, but that is the color scheme that we’ve had for the past 5 years. What color of grout are you doing? Maybe match the grout color to the color of the gray veining in the island countertop. Would you consider a light gray for the perimeter countertops? That would provide a little contrast with the white cabinets and could be a nice complement to the island countertop too.

Actually, relooking at your photo, the chevron is more gray than I was thinking. I
Scratch the gray grout.