This is changing; OpenAI's newer API (Responses) is required to include reasoning tokens in the context while using the API, to get the reasoning summaries, and to use some of the OpenAI provided tools. Google's OpenAI compatibility supports Chat Completions, not Responses.

As the LLM developers continue to add unique features to their APIs, the shared API which is now OpenAI will only support the minimal common subset and many will probably deprecate the compatibility API. Devs will have to rely on SDKs to offer comptibility.

It's still trivial to map to a somewhat different API. Google has it's Vertex/GenAI API flavors.

At least for now, LLM APIs are just JSONs with a bunch of prompts/responses in them and maybe some file URLs/IDs.

It isn't necessarily difficult, but it's significantly more effort than swapping a URL as I originally was replying to.

> There is no "capture" here, it's trivial to switch LLM/providers, they all use OpenAI API. It's literally a URL change.

So? That's true for search as well, and yet Google has been top-dog for decades in spite of having worse results and a poorer interface than almost all of the competition.