How do you use libraries in Flutter?

You can directly call native Android and iOS SDKs of Tokbox chat app from your Flutter application — wherein the UI will be driven by Tokbox SDKs. Since this approach uses native UIs of each platform, the app developer is devoid of any responsibility to create working UIs on both the Android and iOS platforms.

Adding a package dependency to an app

Creating Flutter module

Yes you can . It is helpful if you are using SDK that gives you native code for both Android and iOS, otherwise it will be difficult.