Yes! The vegan queso and/or homemade sour cream can be made up to 5 days ahead of time; the taco meat and refried beans can be made 2-3 days ahead of time; the pico de gallo can be made 1 day ahead of time; the pickled onions can be made up to 10 days ahead of time. The only item that you'll want to make on the same day is the guacamole. For the queso, taco meat, and refried beans, reheat them before assembling the nachos.