User can contact seller directly from product page. Option to set so that user can contact seller only after purchase.
Once activated, user can send message to seller directly from product page.
You can go to Dashboard > Front End PM > Settings > Misc > WooCommerce to set if you want your users can contact seller only after purchase. You can also set in which order statuses customer can contact seller.
Screenshot:
This is a community maintained custom extension. There are lots of plugins for integration, so it is not possible to maintain all. I do not provide support for this extension.