Hi,
Thank you for the warm words about Publii 🙂
At this moment we have no plans for such importer (mainly due many other important features to do), maybe if the amount of requests will increase – we will try to prepare it 🙂
The only solution which I see is following:
1) Export your Wix site to empty WordPress instance: https://www.hostinger.com/tutorials/wix-to-wordpress/
2) Then prepare WXR file from that WordPress
In my opinion it should be enough at this moment 🙂