Please refer to support ticket 1647681.
We are able to create Product List variants based on Product Categories.
There are rules that specifically point to Product Lines, yet it does not work (unclear on why they would be available in the first place.
What can be done in create a Product Detail variant based on Product Brand Product Line.
What is also required is the ability to have Brand Product List variants that can be customized based on Product Lines, the same way we are able to create Product List variants based on Product Categories:
purpose being to either add specific rich content or simply have different widgets and/or match the page settings of the related Product Categories (i.e. mask availability, etc.