I think there's also a missing gap in how to present Swagger beautifully, the default one ( https://petstore.swagger.io/ ) is meh. I'm looking for something that can generate like https://stripe.com/docs/api but open source (since the OP is talking about it).
I imagine a tool(chain) that can take Swagger generated from annotations in code, and combine it with a folder containing Markdown files for "free form" documentation, and generate a Hugo/Jekyll static site that can be deployed in Cloudflare Pages in docs.mycompany.com
When we redid the Mux docs (https://docs.mux.com/api-reference) we actually just decided to build our own renderer. It really wasn't as bad as you might think, at build time we pull in the JSON version of our OAS spec and render it as a static build in our Nextjs app. Don't get me wrong, it wasn't trivial, but the benefit of having complete control over the output has been well worth it.