What experience do you have with internal system integrations?

In my experience working with internal system integrations on Android, I have encountered the need to interact between different application modules and external services via APIs and local data exchange mechanisms. For example, integration with an internal authentication service through REST API, where the app sends requests and receives tokens for further operations.

I also used ContentProvider for data exchange between applications on the device, as well as BroadcastReceiver to respond to system and user events, which allows integrating different parts of the system without direct dependency.

In projects, I applied architectural patterns (MVVM, Clean Architecture), which facilitated the integration and maintenance of internal system connections, and I also used Dependency Injection to manage dependencies between components.