Is it possible to have product specific reviews available on collection pages for those brands?
Unfortunately, the review widget must be tied to a specific product or it will not be able to display reviews.
In this case, I would suggest using our review carousel though that you can feature 5-star reviews or you can choose which.
I can help to install Review Carousel on collection pages for you if you agree :)
Feel free to contact us if you have any questions or need further assistance.