Combine diced onion and tomatoes in a fine mesh strainer.
Season with a few pinches of salt and let drain over a bowl or sink.
Preheat oven to 425°F.
Line a rimmed baking sheet with parchment paper.
Spread tortilla chips in an even single layer.
In a mixing bowl, combine chicken with oregano, chili powder, garlic powder, and cumin.
Add half the BBQ sauce and toss well.
Spread BBQ chicken evenly over chips.
Add corn evenly across the pan.
Top with shredded cheese and jalapeno slices.
Bake for 10–12 minutes until cheese is melted and chips are toasted.
Transfer drained pico de gallo to a bowl and mix with lime juice and cilantro.
Remove nachos from oven.
Top immediately with sour cream, guacamole, shredded lettuce, remaining BBQ sauce and pico de gallo.
Serve immediately.
