Ollama runs on Android just fine via Termux. I use it with 5GB models. They even recently added ollama package, there is no longer need to compile it from source code.
We are a dev toolkit to run LLMs cross-platform locally in any app you like.
With respect to the inference SDK, yes you'll need to install the (react native/flutter) framework inside each app you're building.
The SDK is very lightweight (our own iOS app is <30MB which includes the inference SDK and a ton of other stuff)