ImageGallery allows you to show items grouped by category as a static setting from the controls designer. When you open the control for editing there is a section "Narrow selection" >> "Selection of Images". The problem here is that this does not allow you to set the category dynamically. There is a way to do this by creating some logic that appends the category name in the url which will force the Image gallery to filter its data source.
You need to format the URL of the category so that it is
and after that goes the cateogry name
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