An answer from OpenAI will be very biased. OpenAI will happily take your money to query their models with long prompts. They will also happily take your money to compute embeddings and thus help you search (and lock you in!).

But, as far as I know, OpenAI will not help you fine-tune, they will not run a fine-tuned model for you, and they would probably prefer that you use their models over open models that can be fine tuned.

(None of this is to say that fine tuning is better. I’m just saying that OpenAI has a strong commercial bias.)