I’m sorry, so your position now is that “being completely invisible to the users” is “controlling the UX”?
I can't reply to your child comment for whatever reason, but Siri is part of the Apple Foundation Models framework. The idea is that no matter what backend the developer uses, the end user will always say "Hey Siri." This is analogous to controlling the UX. Siri is independent of whichever model the app developer uses.
It's Apple, so it's some revolutionary big brained play, and not just yet another llm sdk.
I think you're taking the written words a bit too literally here. Read it with a more lax filter and less literal word-meaning, and I think the original comment will become a bit clearer.