Preheat the oven to 350 degrees F.
Lightly coat both sides of each tortilla with cooking spray. Stack the tortillas and cut them into six wedges. Spread out the triangles on a sheet tray. Sprinkle evenly with 1/4 teaspoon salt. Bake until crisp and light golden brown, about 25 minutes. Toss the tortillas halfway through.
Meanwhile, toss the red onion with the lime juice in a small bowl and set aside.
Heat the oil in a large nonstick skillet over high heat. Add the turkey and cook, breaking apart with a wooden spoon, until browned and cooked through, about 5 minutes. Add the butternut squash, salsa verde, 1/2 cup water and the remaining 1/4 teaspoon salt. Reduce to a simmer over medium-low heat and cook, stirring periodically, until the sauce is thick, not watery, and the squash tender, about 10 minutes. Fold in the pumpkin seeds.
Turn the oven up to 400 degrees F. Spread the turkey mixture evenly over the tortilla chips. Sprinkle with the Monterey Jack and Cotija. Bake in the oven until the cheese melts, 8 to 10 minutes.
Garnish with the onions, cilantro, radishes and avocado. Thin the sour cream with 2 tablespoons water and drizzle all over the nachos.