I ran a small food shipping operation four years or so ago until we went under. Shipping frozen food isn’t hard but it does require good insulation and dry ice. We used to buy dry ice in pre-packaged blocks from a distributor. I’d contact rncind.com out of Georgia for insulated shipping boxes that store folded flat, are mostly recyclable, and are more efficacious than the typical styrofoam shipping box so you’ll save on dry ice costs (both buying the ice as well as paying to ship the extra weight).
Be prepared for complaints about shipping costs. We charged our costs only without any mark-up for packaging, dry ice, or UPS/FedEx and people still complained. Those costs would obviously come down with sufficient volume.