you can peel just the shell around the head away. It should make hatching easier... to prevent the membrane from drying out, you can cap it with a large clean egg shell. if she’s still chewing, then she’s not ready... the membrance should look completely clear when you apply coconut oil to it.
I don’t know much about duck hatching, but it seems like it can take 48 hours. Since she can breathe just fine, I would wait until you see her actively struggling to get out...when my chick pipped the wrong end, I was extremely anxious, but she got herself out just fine.