In a large mixing bowl, add chickpeas. Mash with a fork or potato masher until mostly broken down but still chunky (leave some whole pieces for texture).
Add buffalo sauce, vegan mayo, lemon juice, garlic powder, onion powder, salt, and pepper to the chickpeas. Stir until everything is evenly coated.
Fold in diced celery, red bell pepper, red onion, and green onions with a spoon. Taste and adjust spice or salt.
Toast bread slices lightly for extra crunch.
Spread chickpea salad on one slice of bread. Top with lettuce or spinach. Drizzle extra buffalo sauce or ranch if desired. Close with another slice.
Cut in half and serve right away or chill for meal prep.