Must I have a company to sell a product?

First step. Blueprint document patents then incorporate. If you expect success you must be credible. Protect your idea and patent. This keeps people from making all your money. This takes money and if you really think your idea is innovative, then do it. The reasons for having a company are credibility and taxes. Youll never sell even the best of products and services without credibility and you get tax credits for it to boot.