I'm the author, and I definitely know about Swagger/OpenAPI. By coincidence, I'm maintainer of the collection of 250+ Swagger specs for public APIs: https://github.com/APIs-guru/openapi-directory
But I have learned the hard truth over last two years: API catalogs aren't scalable solutions for API discovery. That's why I'm pushing this.
P.S. it is pretty easy to generate Schema.org type based on Swagger/OpenAPI spec.