Whisk tequila, oil, lime juice, cilantro, cumin, garlic powder, salt, and cayenne for marinade together in a bowl. Place chicken slices into a plastic bag, add marinade, and refrigerate for 30 minutes.
Mix sour cream, mayonnaise, lime zest and juice, and enough heavy cream to make crema thin enough together in a bowl and refrigerate.
Remove chicken from the refrigerator and let come to room temperature for 10 minutes.
Meanwhile, preheat the oven to 350 degrees F (175 degrees C). Preheat an outdoor grill for high heat and lightly oil the grate.
Cook chicken on the preheated grill until caramelized and no longer pink in the center, about 5 minutes on each side.
Lay tortilla chips out in a single layer over two cookie sheets. Mix pepper Jack and Mexican cheese together and sprinkle half of the mixture over the chips. Cut the grilled chicken into bite-sized pieces and distribute evenly over cheese. Top chicken with remaining cheese.
Bake in the preheated oven until cheese is melted, 10 to 15 minutes. Drizzle lime crema over nachos and sprinkle with cilantro.