The developer team is working hard to create an integration plugin for WP All Import but their APIs is not enough to do that so the integration will be paused for a time to wait for the WPAI to add more useful APIs in their source code.
I will inform you if there is any information.
Later I have asked wp all import for this, and here is their reply and I quote
Unfortunately, that’s not something we can currently commit to. But, if we receive enough requests we may create such an add-on in the future.
However, if Meta Box lets us know what type of API support they were missing we may be able to add that into a future release.