In a large bowl, combine the chickpeas, buffalo sauce, vegan mayonnaise, garlic powder, onion powder, salt, and pepper and mash well with a fork or potato masher until the mixture has a chunky consistency.
To make the ranch dressing, combine vegan mayonnaise, almond milk, apple cider vinegar, lemon juice, garlic powder, onion powder, paprika, salt, pepper, parsley, and dill to a liquid measuring cup and whisk until smooth.
Use a large bread knife to cut the whole sheet of slider buns in half crosswise. Remove the top and set aside. Spread the buffalo chickpea mixture on the bottom half of the slider buns, then top with lettuce, tomato, and red onion. Drizzle the ranch dressing over the top.
Place the top half of the slider buns back on top. Then slice between the buns to make 12 sliders.