Here are Ubuntu Touch platforms key topics when you want to extend your app with Ubuntu Touch ecosystem:

Content Hub

Each application can expose content outside its sandbox, giving the user precise control over what can be imported, exported or shared with the world and other apps.

Push notifications

By using a push server and a companion client, instantly serve users with the latest information from their network and apps.

URL dispatcher

Help users navigate between your apps and drive their journey with the URL dispatcher.

Online accounts

Simplify user access to online services by integrating with the online accounts API. Accounts added by the user on the device are registered in a centralized hub, allowing other apps to re-use them.

Read the docs

Packaging your app

Here you will get some informations about the confinment model and the packaging system: