Preheat the oven to 375 degrees F. If the 15oz chili is cold, warm it until heated through (microwave or stovetop) or use at room temperature as desired.
Choose a large oven-safe pan or baking sheet. Divide the 6-8 large handfuls of corn tortilla chips into two roughly equal portions.
Spread one portion of the chips in an even layer on the pan.
Spoon half of the 15oz chili over the chips in an even layer, then sprinkle half of the 1 1/2 cups cheddar cheese, shredded, and half of the 1 1/2 cups pepper jack cheese, shredded, evenly over the chili.
Repeat the layers with the remaining portion of chips, the remaining half of the 15oz chili, the remaining half of the cheddar, and the remaining half of the pepper jack.
Bake in the preheated oven for 10–12 minutes, or until the cheese is fully melted and gooey.
Remove the nachos from the oven and quickly top evenly with 1/2 cup sliced black olives, 1/2 cup sliced pickled jalapeños, 1/2 cup diced tomatoes, 3/4 cup sour cream (spoon or dollop as preferred), and the 2 green onions, diced.
Serve hot with a side of salsa.