This provides a single node openai > Open AI query node that takes a system prompt and user message and sends them to chatGPT 3.5 Note, you MUST have an OPEN AI API key stored in the environment variable OPENAI_API_KEY in order for this to work.
https://github.com/nagolinc/comfyui_openai_node
git clone https://github.com/nagolinc/comfyui_openai_node
comfy node install comfyui_openai_node