Android LiveData Shared between activities by Application Session
Is a good practice to share LiveData?
Yeah

Here as you are using the data in databridge as a single source of truth and it is used hold data which is needed to be shared across multiple screen with live updates, Livedata is a really good option as it will also handle the lifecycle for you.

Android docs also has sample on Extending LiveData to create your own singleton data source which you may find helpful.

Also you can leverage the feature of Object declarations in kotlin to lazy initialize your DataBridge rather than in Application class.