Pat the chicken tenderloins dry with paper towels and set aside.
In a medium bowl, whisk together the egg, buttermilk, pickle juice or hot sauce, flour, salt, garlic powder, paprika, and black pepper until smooth. The batter should be thick enough to coat the chicken.
In a separate shallow bowl, whisk together the flour, cornstarch, salt, garlic powder, onion powder, paprika, and black pepper.
Dip each chicken tender into the wet batter, letting the excess drip off slightly, then dredge in the dry coating. Press the flour mixture onto the chicken so it sticks well. Place the coated chicken on a plate or wire rack while you finish the rest.
Heat oil in a large heavy-bottomed skillet or Dutch oven to 350°F.
Fry the chicken tenders in batches for about 4–6 minutes, turning as needed, until golden brown, crispy, and cooked through to 165°F. Transfer to a wire rack or paper towel-lined plate.
While the chicken cooks, make the honey chipotle sauce. In a small saucepan over medium-low heat, whisk together the honey, BBQ sauce, adobo sauce, apple cider vinegar, Dijon mustard, garlic powder, chipotle chili powder, and salt.
Simmer the sauce for 3–5 minutes, stirring often, until smooth, glossy, and slightly thickened. Whisk in the butter at the end, if using.
Add the crispy chicken tenders to a large bowl and drizzle with the honey chipotle sauce. Toss gently until coated, or brush the sauce over the tenders if you want to keep them extra crispy.
Serve warm.