Eaten here a handful of times, never had a reaction... and did I mention this is the best pho I’ve ever had in North America, hands down? The menu clearly states that al items are “gluten free.” The only thing maybe not is the hoisin available on tables (usually contains gluten so I didn’t even try).
So good, don't have the soy sauce or hoisin and you are 100% GF. Never had a single issue! Worth remembering to stop by the ATM.