This isn't Claude specific. Developers can also write apps that call Google's server based Gemini models.

> At WWDC, Apple announced that it's opening its Foundation Models framework to third-party cloud model providers. Starting with iOS 27, macOS 27, iPadOS 27, visionOS 27 and watchOS 27, model providers can implement the new public LanguageModel protocol to provide a common interface for model inference. We've made Gemini models available to the Foundation Models framework through the Firebase Apple SDK.

This provides a fully native development experience — cloud-hosted Gemini models can plug directly into the Foundation Models framework using the same API. That means the on-device Apple model and cloud-hosted Gemini models sit behind a shared API surface, so you can easily swap between local and cloud inference to fit your use case.

https://blog.google/innovation-and-ai/technology/developers-...

The important part is Apple rebranding “OpenAI-compatible API” to “language model protocol” and I think we should all rally around this immediately before we’re cursed with that awful tongue twister.