Gotcha. I think this might be where Protobuf falls short because you have to "source" the tooling for all its different outputs, but support for OpenAPI 3.0 spec generation has existed for over a year.
Amazon is great at a lot of things, but AI and Machine Learning aren't it. From what I saw when I worked there, they don't have the talent to produce their own models (which is, I think, what we all expected to see), but the surprising thing is that they haven't partnered yet.