Mix beef chuck, beef broth, onion, red wine vinegar, 2 tablespoons chili powder, garlic, 2 teaspoons cumin, salt, and black pepper together in a slow cooker.

Cook on High until beef is tender, about 4 hours. Transfer beef from slow cooker to a cutting board. Shred using 2 forks. Return shredded beef to the slow cooker. Cook on High until flavors combine, about 1 hour. Drain excess juice.

Combine flour, baking powder, and 1 teaspoon salt together in a large bowl. Pour in milk; mix until a dough forms.

Knead dough on a floured work surface until smooth, about 5 minutes. Let dough rest, about 5 minutes. Divide into 4 equal sections and roll out into 1/4-inch thick rounds. Poke a hole into the center of each with your finger.

Heat vegetable oil to a depth of 1 1/2 inches in a deep-fryer or large saucepan to 350 degrees F (175 degrees C). Fry each dough round until golden brown, 1 to 2 minutes per side.

Heat 1/4 cup olive oil in a small pot. Add pinto beans, 1 tablespoon chili powder, 1 teaspoon cumin, garlic powder, salt, and black pepper; stir and mash until heated through, about 5 minutes.

Top fry bread with pinto bean mixture and shredded beef.