It sounds like you want the Data view to listen to the Tree view. You cannot do this the same way you would with a data grid, so instead, you can accomplish this by setting the Tree view up so that a microflow fires when you click on a row. In that microflow, you should set an association to the selected entity and refresh the object where you're setting that association.
For example, consider a situation where you have Order and OrderLine entities in your tree. You could have your page host a non-persistable context entity called "ABC". ABC should have an empty association to an OrderLine.
Now on your page, you should have the context entity (ABC, created via microflow), and then inside that your Tree view and a Data view of the type OrderLine. Upon clicking an OrderLine row in the tree, your microflow should take an ABC and an OrderLine as parameters, set the association between ABC and the OrderLine, refresh the ABC entity. This should give the effect of displaying the OrderLine entity in the Data view on your page.
I hope that makes sense.