Clone Volumes / Taking Backups

If an app requires to be shut down before backups can be taken (e. g. for DB consistency), there seems to be no way atm for volumes to be accessed or mounted in other apps, right?

Another question / solution could be to shut down the app (scale 0) and then make a clone of the volume to be attached by another app that syncs the clone to somewhere external afterwards. Would this be possible somehow (if not feature request :-)?

Or are there any other ways of accomplishing backups from volumes when it’s guaranteed that the app was shut down properly before?