I would think the cavity will be filled with insulation and if you remove it and install there this empty brick you will be leaking heat through this place which will be significantly coolder/noisier.
The article image showed it install high on the wall, in what would be the attic. And there are alternate designs that are normal depth, but multiple bricks tall and wide.
Potentially but in the photo it is installed in a gable which aren't usually insulated.
Swift bricks are a fully enclosed unit (other than the hole on the outside)