Cook fries according to package instructions (oven-baked or deep-fried) until golden and crispy, then season with salt.
Heat olive oil in a skillet over medium-high heat, add finely chopped onion and sauté for 3–4 minutes until softened and slightly golden.
Add minced beef to the skillet, breaking it apart with a spatula, and cook for 8–10 minutes until browned and cooked through. Season with garlic powder, salt, and black pepper and cajun seasoning.
While the beef cooks, make the spicy mayo by combining mayonnaise and sriracha in a small bowl and mixing until smooth.
Divide the cooked fries between two bowls as a base layer, then top generously with the seasoned minced beef mixture.
Scatter shredded cheese over the hot beef so it begins to melt naturally from the heat.
Drizzle spicy mayo and sweet chili sauce liberally over the top.
Serve immediately while the cheese is melted and the fries are still crispy.