Place one oven rack in lowest position and another rack in highest position. Preheat oven to 450ºF. Mix oil, spices, 1 3/4 teaspoons of the salt and pepper in a large bowl with wire whisk. Add squash; toss to coat evenly. Arrange squash in single layer on parchment-lined shallow baking pan. Set aside.
Arrange pineapple slices in single layer on a separate parchment-lined shallow baking pan. Drizzle with 2 tablespoons of the lime juice.
Place pan with squash on lowest oven rack. Place pan with pineapple on highest oven rack. Roast 30 to 35 minutes or until squash is tender and lightly browned, stirring squash and flipping pineapple halfway through cooking.
Meanwhile, toss cabbage with remaining 2 tablespoons lime juice and 1/4 teaspoon salt in large bowl.
Remove squash and pineapple from oven and let cool slightly. Chop pineapple into bite-size chunks. To serve, layer squash and pineapple in warm corn tortillas; top with cabbage or radishes and chopped white onion, if desired.