I think the real story here is auto embeddings:

  https://manual.manticoresearch.com/Searching/KNN#Auto-Embeddings-(Recommended)

and hybrid search:

  https://manual.manticoresearch.com/Searching/Hybrid_search#Hybrid-search

With these two features you can set up RAG with hybrid search in about the time it takes to install the server and insert the documents.

Manticore is really performant and uses far fewer resources than similar search engines like elastic.