But in Copilot Chat in MS Office for example, isn’t the LLM itself Copilot? That’s what I’m talking about as being a weak LLM — I know originally it was some variant of ChatGPT.

GitHub Copilot now is less a model and more a router. Kind of a pity, they had a solid lead there. I at least used it to complete yaml and json configs and it made fewer typos than me.