That said, I'm not sure why this would be better
than just taking nitric oxide
One might do well to start with the assumption that "taking XYZ orally" is not as effective as producing it naturally.The digestive system involves a pit of acid and a diverse, poorly-understood, and variable biome. It is an extremely fraught and indirect way to introduce substances into the body. Obviously many things can be introduced this way, but the list of those that can't is probably longer than the list of things that can.