So possibly not even twelve hours ago yet, and definitely not 24 hours ago? Sometimes they kind of punch around and enlarge the pip without actually being trying to zip.
It can breathe and it hasn't been trying to hatch for more than 15 hours max, so for now you're safe to not assist if you don't feel comfortable and see if it will hatch on its own. It won't die at this point if you don't assist right away.
You could open the end of the air cell without hurting it, if you wanted to, but you would also have to be ready to apply coconut oil or bacitracin to the membrane if it's not ready to hatch and then monitor it to reapply as needed. Ducks are really slow hatchers and some take up to 48 hours from the time of the external pip to actually zip and hatch.