Heat oil; add onion and sweat the onion. Add ground turkey and cook until all pink disappears. Add garlic and sauté until garlic is fragrant, about 45–60 seconds. Stir in pinto beans and chili sauce. Heat to 165 degrees. Blend in browned turkey mixture. Portion 1/4 cup corn chips into a serving bowl. Top with 3/4 cup turkey mixture. Sprinkle each with lettuce, tomatoes, and Cheddar cheese.