There's quite a bit of detail behind the
recently spied G26 4 Series Gran Coupe prototype's mesh if you play around with the image - you can definitely see the outline of the grille and how it closely matches the concept. Looks a tad bit more rounded around the corners to me and will likely have a pretruded nose like the concept as well.
I see it very much like a 2020 M135i face with its grille elongated vertically... with a wider track of course.
Spy photo: