Landing a purchase order from a major retailer can feel like the moment a brand has arrived. For years, the business may have been built order by order: a Shopify store, an Amazon listing, a wholesale account, a product that found its audience. Then a buyer from Walmart, Target, Kohl’s, or another national chain says yes. The order is larger. The brand is more visible. The opportunity is real. So is the operating burden that comes with it. Large…