I've recently posted an article detailing how to call the Graph API to do a document search in Power Virtual Agents, that returns a list of matching documents from a SharePoint site, with links.
Here, we go one step further and show how to summarize internal content with a ChatGPT or GPT-4 OpenAI or Azure OpenAI Service model. GPT models are able to summarize and give a more user-friendly response to the user.
This is the end-result (using the PVA chatbot component in Power Apps, now in preview):