In addition to what @Sneha-Parmar mentioned with custom actions, if you have RTCDP destinations you can use the "Update Profile" action in your Journey to update profiles to include in a Facebook activation segment. Then in the Facebook destination you can grab an exported audience based on segment definition.

In addition to @Ryan_Morales suggestion, you could look to set a rule within launch to perform to set a key value pair on the device, or go to a URL path. Attach or Modify data actions might work for this. That might be a way to trigger a feature flag. Do you have a conditional rule that you are looking to add before you trigger the update on the client app?

Hey John - you will find most of the information you are looking for on our dedicated Mobile SDK doc site: https://sdkdocs.com Most of the tags are not deployed in Launch, but can be controlled via Launch. Typically a trackAction or trackState call is made within the app to denote a button press or view switch etc. With each one of these calls you can attach additional context data. Data Elements can be created within Launch to alias the data flowing through the mobile app for additional control...

So it seems like instead of "Attach Data" you want to use the "Modify Data" action. Ahead of the ACTION you would want to put a condition on the event. Or use the Mobile Core TrackAction event as your trigger.