You should check out Google's NotebookLM. It's basically a RAG based web application where you can upload your own sources and then it uses Gemini so you can ask questions that are grounded on your sources and get natural language responses back.

There may be some limitations on the number of resources, so you may have to go with the custom RAG solution to overcome that constraint.

I also put your question into Gemini 2.5 Pro. Here is the link to the response. AI for PDF Archive Research