I write all of my openapi specs by hand. It's not hard.
I imagine you are very much in the minority. A simple hello world is like a screen full of yaml. The equivalent in graphql (or typespec which I always wanted to try as an authoring format for openapi https://typespec.io/) would be a few lines
Do you validate responses from client-side and server-side(Fastapi does this and prevents invalid responses from being sent) from spec?
I imagine you are very much in the minority. A simple hello world is like a screen full of yaml. The equivalent in graphql (or typespec which I always wanted to try as an authoring format for openapi https://typespec.io/) would be a few lines