I was thinking more in terms of compliance, is it legal to sell medical tech without FDA certification?

This is without getting into Physician licenses if we consider the product to be physician state advice.

Regulatory oversight of medical tech is important. But it's not because of the law, it's because it's a matter of life and death. The legality aspect becomes less interesting when there's no functioning regulatory framework that protects the people.

Which is to say, OpenAI getting approval wouldn't make this any better if that approval isn't actually worth the paper it's written on.