Ceviche to me is like sushi, albeit marinated or cooked with citrus and chilies. My first exposure to ceviche was in Ecuador. Looking back at it, this version is a shrimp "cocktail" style. I believe that the Ecuadorians fear raw fish, which explains a a short semi-cooking or longer marinade in salt and lime. With chiles less a common condiment than mustard and ketchup, it's less spicy.
For garnishes, Peruvians use corn and sweet potatoes, whereas Ecuador prefer plantain chips, popcorn and there is various Asian immigrant influences including Nikkei (Japanese) and and Chifa (Chinese) flavors. Peruvian restaurants such as Brooklyn's Llama Inn are my go-to Peruvian cervice place. But with Covid limiting us to take-out, I prepared an at-home Peruvian styled corvina fish classic, which resulted in awesome depths of textures and taste.