Deleting photos / videos from the iOS Camera Roll that have been either imported into Lightroom Mobile and/or successfully sync'd to the cloud would be a great workflow improvement. Having to manually go back to the camera roll, determine which photos have been imported / sync'd in Lightroom Mobile is a huge pain.
The ability for apps to delete photos from the Camera Roll has existed since iOS 8, released in 2014. I'm stumped as to why this features does not yet exist in Lightroom Mobile. The workflow is ackward and painful without it.
https://developer.apple.com/reference/photos/phassetchangerequest