Yes. If you're the type of seller who likes to batch your work, Drafts are for you.
Once you start a listing, you can save it to your Drafts instead of publishing right away. You'll find your saved drafts under Listings.
You can edit and publish a draft from either the app or the web.
One note: starting a brand new listing is still available in the PangoBooks app only. Once it's saved as a draft, you can finish it wherever you like.