On iOS 27 Beta 1, it looks like the user must enable either "Siri"/"Hey Siri" or "Press Side Button for Siri" in iOS settings for SystemLanguageModel.default.availability to report true. Otherwise, it returns .appleIntelligenceNotEnabled.
Is this expected behavior? This doesn't seem very intuitive. The user might very well want to use in-app AI functionalities without wanting to talk / press side button for Siri. Also, with the new "pull down for Siri" UX these are not the only way to interact with Siri anyway.