I agree with what you wrote. The whole situation reminds me of the old "Standards" XKCD, to an extent. In the short term something like LiteLLM, which I just discovered doing more research on the whole topic, can at least hide some of the underlying complexity.

That being said, considering what you've done with Open Home and Home Assistant (which has run my home for years, thank you!), perhaps there is some hope of an open standard in the near future.