Gallery input type is for images galleries. Just as the gallery used for products images. Take a look at “gallery” default attribute (or may be in sample data).
You could have several galleries for an attribute set.
Is there any documentation on the gallery attribute type? I’ve been searching for hours and can’t find any documentation or descriptions on how this can be used. I am assuming it’s an easy way to maintain multiple images for products, but I am lost as to how to set that up. Examples would be great. (any help would be great). Thanks!