To build a mobile app with live streaming and chat features, you can take advantage of several SDKs, frameworks, and APIs that simplify the process. For example, Agora and Twilio offer robust SDKs for live streaming and real-time communication. If you're looking for a more flexible solution, Firebase can be useful for real-time chat functionality, while Wowza provides live streaming APIs.
If you're thinking about extending the app to a web platform, you can also explore how to build live streaming website using similar technologies. This way, you'll have both a mobile and web presence for your live streaming app.