Preheat the smoker to 250°F. Shape a small piece of foil into a shallow tray or use a small smoker-safe loaf pan to support the meatloaf.
In a large mixing bowl, combine the ground beef, egg, almond flour, chopped onion, Worcestershire sauce, garlic powder, smoked paprika, salt, and black pepper. Mix gently until evenly combined, taking care not to compact the mixture.
Shape the mixture into a compact loaf and place it on the foil tray or in the loaf pan. Set it in the smoker and cook until the center reaches 160°F, checking with an instant-read thermometer.
While the meatloaf smokes, stir together the sugar-free ketchup, apple cider vinegar, and Dijon mustard in a small bowl.
When the meatloaf is nearly at temperature, brush the glaze over the top. Continue smoking until the center reaches 160°F and the glaze looks set.
Remove the meatloaf from the smoker and let it rest for 10 minutes before slicing. This helps the slices hold together.