Whisk buttermilk, salt, and pepper in a bowl. Add chicken and marinate 15 minutes while you preheat oven to 425°F.
Mix flour, panko, garlic powder, and ranch mix on a plate. Dredge tenders, pressing crumbs on both sides.
Bake on a greased sheet 12–15 minutes, flipping once, until internal temp hits 165°F and crumbs are golden.
Mix hot sauce and melted butter; toss baked tenders in sauce for even coating. Kids will like the heat if you cut sauce 50/50 with extra butter.
Stir mayo, sour cream, blue cheese, lemon juice, and chives for the dip. Serve chilled alongside hot tenders.