In a large bowl, mash the chickpeas with a fork or potato masher until mostly smooth, leaving some chunks for texture.
Add the vegan mayonnaise, Dijon mustard, lemon juice, celery, red onion, dill pickles, garlic powder, onion powder, salt, and pepper to the mashed chickpeas. Mix well until all ingredients are combined.
Taste and adjust seasoning if necessary. If you prefer a creamier texture, add more vegan mayonnaise.
Spread the chickpea salad mixture evenly onto two slices of whole grain bread. Top with lettuce leaves and place the remaining slices of bread on top.
Cut the sandwiches in half and serve immediately, or refrigerate for up to 2 hours before serving for a chilled option.