You best bet (today) is actually to not train a model, but instead use a model but connect it to your docs via vector search. For example: https://python.langchain.com/en/latest/use_cases/question_an...

I heard about something like that, https://gerev.ai

They are working on exactly this, and it's even open source and self hosted I guess..

Probably want to check out https://www.kapa.ai/, no affiliation, just a fan.

GPT4 + retrieval might be the fastest path. But quality not guaranteed, and assuming you do not mind uploading all your private info to openAI.

This project might be the best option where you can finetune an LLM on your data and keep the model yourself

He asked specifically for self hosted solutions.