Hi @radicalrooster, thanks for your message.
You can add a collection list first the Category collection template page and bind that to the Category collection
Then insert your elements into the collection list and bind your element to the reference field you wish to show and set a filter( Filter Collection Lists ) to only show the elements where there is a matching reference for the current category.
To help further, could you help to share your project read only link ( Share a project’s read-only link).
Thanks in advance