I found this thread for a Gen 3. Quick question, is it the same for Gen 4, just pull up? No fasteners? Removal of engine cover | PriusChat
Be careful as I cracked mind on a cold Texas morning. Now I will use two fingers, one on each side of the fasteners, and pull straight up.
Not sure how/if it'd work on 4th gen, but with our 3rd I put my thumbs on the edge of the bottom-of-windshield edge, grip under the ends of the cover at both ends with my fingers, then just moderately pull up. It slowly, slowly loosens, then pops off against that windshield edge.