Prepare the chicken: Use rotisserie or boil chicken breasts in a pot of salted water for 15–20 minutes until the internal temperature reaches 165°F. Shred using two forks OR a hand blender.
Make the buffalo dressing. In a large bowl, combine the Greek yogurt, mayonnaise, Frank's RedHot sauce, garlic powder, salt, and pepper. Stir everything together until well combined.
Add the mix-ins. Add the shredded chicken, finely diced celery, and green onion to the bowl with the dressing.
Toss and serve. Mix everything together until the chicken is fully coated in the creamy buffalo dressing. Taste and adjust salt, pepper, or hot sauce as needed.
Serve immediately or refrigerate for at least 30 minutes for best flavor.