On the legal side, I've got business insurance, which thankfully isn't that expensive. I've been holding off on forming an LLC since that's gonna run me about a grand here in CA including the cost of setting it up and LLC tax, but if there's continued interest in the product, I'll do that soon.
Edit: Also AAFCO is a group that has standards for this sort of thing that are pretty straightforward: https://petfood.aafco.org/Portals/1/pdf/eight_required_labei...
https://www.lobbplewe.com/blog/2019/09/rules-for-out-of-stat...
Why an LLC instead of an S-corp?
"The FDA’s regulation of pet food is similar to that for other animal food. There is no requirement that pet food products have premarket approval by the FDA. However, the Federal Food, Drug, and Cosmetic Act (FFDCA) requires that pet foods, like human foods, be safe to eat, produced under sanitary conditions, contain no harmful substances, and be truthfully labeled."