I have no idea if drywall would be a suitable substrate for stucco but instead of learning how to stucco, you might consider FRP (fiberglass reinforced plastic) panels. They're water resistant, easy to clean, and are commonly used in restaurants, public restrooms, etc. The most common form is white with a pebble finish but it's available in a number of colors and finishes (obviously at a higher cost). Home Depot gets about $30 for a 4x8' sheet of the white pebble stuff. You'll also need some channels for the edges and between sheets. It's glued in place over the existing drywall.

I have no affiliation with the companies but two that manufacture the product are Marlite and Crane Composites. Either site will give you some idea of what's available.

We have steel sheets for the walls and ceiling of our garage (same as what is used on the outside of pole barns). It was easy to install and has been crazy easy to keep clean.

Thanks both of you. I am looking at the plastic (FRP) option. Looks really nice. The only question I have is the climate. My garage is insulated but not heated. We can get 90 during summer and down to 10F during winter. Is that going to be a problem? Is it going to deform/buckle/warp? Would really hate to have to replace in a couple of years.

Thanks