Combine ground chicken, green onions, ranch seasoning, 1/2 teaspoon salt, 1/4 teaspoon pepper, cheese, and 2 tablespoons Buffalo sauce in a bowl. Mix well; spread evenly all the way to the edges of each flour tortilla.
Heat a griddle or pan over medium-high heat. Coat lightly with oil and place tacos, meat side down onto the griddle. Cook 5 minutes, undisturbed, until browned and cooked through. Flip tortillas and cook 1 minute longer.
Meanwhile, toss cabbage, celery, carrots, blue cheese, vinegar, olive oil, sugar, and remaining salt and pepper in a large bowl until well combined.
Serve slaw on tacos and drizzle with remaining Buffalo sauce.
