Preheat a smoker to 250°F. Line a rimmed baking sheet with foil, or prepare a grill-safe pan for the meatloaf.
In a large bowl, combine the ground beef, blue cheese, crumbled bacon, panko, egg, diced onion, milk, salt, and black pepper. Mix gently until just combined, taking care not to compact the meat.
Shape the mixture into a loaf on the prepared pan. Stir the ketchup and yellow mustard together in a small bowl, then spread the mixture over the top and sides of the loaf.
Place the meatloaf in the smoker and cook until its center reaches 160°F, checking with an instant-read thermometer. Let it rest for 10 minutes before slicing.
While the meatloaf smokes, heat the oven to 425°F. Toss the halved potatoes with the melted butter and Buffalo-style hot sauce, then spread them cut-side down on a rimmed baking sheet.
Roast the potatoes until tender inside and browned at the edges, turning them once during cooking. Sprinkle with the chopped chives just before serving.
Slice the rested meatloaf and serve with the Buffalo-roasted potatoes.