you can access a node that you have previously executed as long as it is connected to the current node, like this: $("code").item.json for the current item $("code").first().json for the first item
That’s slightly different as the Q/A chain is a complex node. In that case I believe you would have to set up a manual chain of LLM and vector store (like Pinecone node) and then you should be able to read the vector output further down in the flow.