If not all, much of it can be done within VSCode's preview pane on Markdown files with right extensions (and probably out of the box as well) so not sure what's

If not all, much of it can be done within VSCode's preview pane on Markdown files with right extensions (and probably out of the box as well) so not sure what's the value here or maybe I am not the right target audience for this. What could be interesting is a full featured Open API workbench from JetBrains that has full autocomplete, lets you split files with JSON pointers, allows visually adding documentation, examples, schema and such and not only that, generates a mock server based on API specs all the time from examples and if not from examples then using something like faker or LLM so your API is always GET /api/myendpoint ready, there's no need to "click that button, start a server" thing. It is always on the given endpoint. Swagger Editor and friends are not quite there. Commercial web based offerings are also... not that easy to use. Would love some suggestions if something exists already.