This might not be necessary, as Google supports the OpenAI API. I tested it with adding, e.g.:

{
    "model": "gemini-2.0-pro-exp-02-05",
    "url": "https://generativelanguage.googleapis.com/v1beta/openai/",
    "apiKey": "key",
    "enableStreaming": true,
    "developerMessageSettings": "developer"
}

and i was able to chat.

However, tool calls do not work. The tool gets called but then it hangs forever. @eneufeld Do you have any idea?
You can create an API key with free tokens (rate limited) here: https://aistudio.google.com/