You seem to have a fascination with rare and endangered fish species. I will suggest again that you contact CFI. https://www.conservationfisheries.org/
Volunteer, apply, go to events, CFI groupie, whatever. This is your best bet to get an introduction into this world.
Laws exist to prevent trade in fishes that are imperiled. Unfortunately they also prevent a very viable method of arking these species. It is a fine line at the precipice of a slippery slope. Align yourself with those who are doing this above board if you want to make a difference.
I am certain that importing pupfish won't be legal. That aside, the health inspections would likely be cost prohibitive on a species that you wouldn't be able to sell offspring from. Which really is the entire point of these laws.