Heat avocado oil in a skillet over medium-high heat. Add the chopped onion and sauté for 5 minutes until soft and fragrant. Then stir in garlic for 1 minute before adding ground beef, breaking it up as it cooks. Sprinkle chili powder, cumin, chipotle powder, red pepper flakes, salt, and pepper, and cook another 4 minutes until everything is well combined. Drain excess grease if needed.
Preheat your oven broiler to high and place a baking sheet with parchment paper on the top rack. Arrange your low carb chips evenly, spoon the seasoned beef over them, and sprinkle shredded cheddar on top.
Place the nachos under the broiler for about 2 minutes until the cheese melts and bubbles. Remove from the oven and immediately add your favorite toppings like sliced jalapeños, avocado, lime wedges, cilantro, and sour cream. Serve while hot.