It's entirely possible without OpenAI doing anything else. Design your tasks to be repeatable and small steps, call the OpenAI API and log all requests/responses.

Filter out any bad responses and take a representative sample of the data you have collected from OpenAI,and train a Mistral or Llama2 model with the request/response pairs.

Measure the quality of your model vs OpenAI for the same inputs, and then swap out the model in your workflow once happy with the results.