RUM: add support for monitoring iOS and Android applications

Our front-ends are web (React), iOS (Swift + Objective-C) and Android (Java, transitioning to Kotlin). Native apps are trending to become the main channel to access our services (2 mln monthly active users).
The backend is currently on a journey to be fully covered with Elastic APM. We are now revising options for front-end monitoring, and with the release of source maps, the JS RUM looks more promising than before. But there is no coverage for native apps which negates the benefits of having Elastic APM for the front-end stack.

I saw the comment this February that you're looking into this direction. But as of now, I don't see any activities (GitHub repos?) in this direction.

Is there a roadmap for these RUM agents?
Are there integration guides which we could use if we decide to build agents ourselves? if we go in this direction we would definitely open-source them