I don't know how that could be done within Pinot itself, but the Swagger UI is basically an HTML page that loads up the Swagger JS distribution, does a request to the OpenAPI specification for some API and then builds the page content. So, worst case scenario, you could build your own app that serves behind TLS somehow (via the app server or some reverse proxy that handles certificates) and then build the same thing but loading from the Pinot OpenAPI specification.