It seems very silly that we can’t do this?
When you edit the ‘color’ of a tag, all you get is color wheel options, or browse to an external image file. The Sketchup materials are compressed files that you can’t browse to in this manner. The materials are already available in the model, why on earth can’t they be accessed through the tag editor? This would make assigning materials to imported geometry a total breeze! Please add this feature!