Drain and rinse the chickpeas thoroughly under cold water. Place them in a large bowl and use a fork or potato masher to mash about three-quarters of them. Leave some whole chickpeas for texture and visual appeal.
Finely dice the celery and slice the green onions. Chop the fresh dill and pepperoncini peppers into small pieces so their flavor distributes evenly throughout the salad.
In a small bowl, combine mayonnaise, Greek yogurt, Dijon mustard, garlic powder, oregano, black pepper, salt, and pepperoncini brine. Stir until smooth and fully blended.
Place the shredded chicken into the bowl with the mashed chickpeas.
Add the celery, green onions, dill, and chopped pepperoncini to the bowl. Pour the dressing over the mixture and stir until every ingredient is evenly coated.
Taste the salad and adjust seasoning if needed. Add extra pepperoncini brine for more tang or additional pepperoncini peppers if you enjoy a stronger kick.
Cover the bowl and refrigerate for at least 30 minutes. Chilling allows the flavors to meld together and creates an even more delicious salad.
Serve cold on sandwiches, wraps, lettuce cups, crackers, or over a bed of greens. Garnish with extra dill and sliced pepperoncini for a beautiful presentation.