How best to do RAG/Chat search now?

I am looking to add a chat interface to query an email group archive. It’s not clear to me, with version 2.13, what the preferred way to use Opensearch to build this is. Do I use the new RAGTool? Do I use a Conversational Agent? Do I do something like outlined here:

I understand that this is all under active development. But I’m having a difficult time figuring out how these various things fit together (or don’t).

Thanks,
Mark