There’s work and talk on manual stops now. Possibly this could be connected although it does add some issues, e.g. one can no longer speak of a backup success if one has only had success on a backup part. Presumably there would also be some GUI additions so it might wind up getting into more extended code.
Stop after Upload is a current discussion (but there are probably quite a few other topics about the issue).
Fix ‘stop after current file’ #3836 is the coding though it seems somewhat TBD how things should behave.
There’s also talk in those of the “synthetic filelist” which is the start plus changes so far. It’s now meant for resumption of an interrupted backup, but could possibly be leveraged into a periodic snapshot of progress.
except “complete” would be a checkpoint, and might not get the full treatment a finished backup would get.