It is possible to add a taxonomy term linked to a product (or variation) as an entityreference filter for product type (or variation type), but it seems that the same behaviour is not possible with product attributes used in the variations.
Create a views of variations
Add the Relationships: Product variation using attribute_ your attribute
Try to add your attribute as filter: it does not appear in the list as entityreference filter
I made the following merge request
Needs review
2.0
Code