Please stop spreading so much misinformation. Installing a sandboxed app on GrapheneOS is safe, if it is in a seperate profile (to block IPC) and doesnt get random permissions, by the user.
If GrapheneOS would integrate AI, that would be fully FOSS and on-device.
Google is moving lots of core components like Webauthn to play services, to directly deploy updates to all Androids, without relying on the vendor shipping any updates.
Those things would still be installed as a sandboxed app, and only the data you give such a thing (be it an AI blackbox or any random internet platform we use today) lands in Evil Corps hands.