I could see this being not dependent on any third party apis too 1. pgVector 2. huggingface or sentence embeddings like sentence-transformers/all-MiniLM-L6-v2

I could see this being not dependent on any third party apis too 1. pgVector 2. huggingface or sentence embeddings like sentence-transformers/all-MiniLM-L6-v2 3. openassistant or some other open model for the chat part which you could fine tune on your own documents to get jargon and style down.