You misinterpreted my comment there. When I said "I have yet to see a convincing demo" I was talking about the idea of fine-tuning a model to answer questions against documentation. The rest of my comment described RAG - the exact same approach that tgittos is recommending.
Here are a few of my own RAG implementations - getting a basic version working really is something that can be done in a few hours... but getting a GOOD version working takes a LOT longer than that.