Ask HN: The easiest way to build an LLM application?

I have a fair idea of the LLM ecosystem. (Thanks to this very nice blog called Emerging Architectures for LLM Applications). The problem is, there are way too options in each component. ( For E.g, too many vector store implementations, ingestion engines etc) What is the easiest way to get started? Primarily around RAG on my own pdf files.

Also, what is the best/easiest option for hosting?. That blog lists vercel,streamlit, streamship and modal. I know vercel at a high level and found it very good. I am not well versed with javascript/typescript though. I believe the best option for UI generation is to use one of their templates.