Both OpenAI and Google Vertex AI provide to build in knowledge of the domain into the model.

I have a ticket selling platform, with a documentation for event managers how to use it.

I would build a chat applicaiton where they can ask specific questions about the platform. I would not deal with different wording and diffeent languages, but only compose one JSON or CSV and upload to the AI platform. Which platform would you recommend me or what other consideration would you recommend me to add domain knowledge?