Wow I have to admit not. Is there a food research organisation in the US the equivalent of Campden BRI in the UK? If all else fails they do work internationally but are a bit spendy.
Obviously you need to convene the HACCP team to discuss. Things I'd think about is what could be in the dry powder which could survive whatever heat processes you are using to dry it or recontaminate it. Some of the heat processes for some dry ingredients are surprisingly mild. Don't assume they will kill everything and obviously spore formers will be there.
Then I'd think about the consumer. Is it likely to be infants (even if that's a degree of consumer misuse) as then you'd need to start being even more cautious.
Lastly think about how the consumer will then rehydrate. Are they likely to leave the rehydrated drink at room temperature? So have a risk of sporulation of spore formers? If it's an energy mix will there be sugar sources in there? Will there be pH control to prevent some of that happening?
I'm sure there are people on here to help much more than I can. Good luck!