The new "GPTs" feature of ChatGPT allows users to create their own "assistants" with custom prompts and API integrations. You provide the system prompt and a json OpenAPI spec, and the chatbot automatically interfaces with the API for you.
I've created a proof of concept - it works pretty well, although I'm still tuning it. But it is a great help for combing through my library of 3000+ raindrops.
However, there's no doubt that an official plugin would do a much better job! Even an official OpenAPI spec would be a great start. I have put one together from the Swagger and Markdown files in the docs GitHub repo, but it's not complete or particularly robust.
Also, I'm having trouble with the OAuth flow configuration.