Apple and Mistral are not in the same market.

Siri is a minor part of the Apple ecosystem. Fundamentally, it can call into a better LLM provided by a better company. Siri's only utility is that it has access to your iData and can control your iDevices.

Apple sells devices. They have benefited a lot from their devices being good (Apple Silicon).

Mistral sells LLMs. They would benefit from having good LLMs.