I have done something similar with the product description by splitting the description into short and long description. I was hoping to do the same with the collection section!
Or use metafields.
I found an easier solution by using the split filter to get the first part of the description. Then I added custom liquid section to get the second part of the content. As for the subcategories, I used css to get the buttons.
Fellow Shopify Store Operator here. I’m switching from the Debut Theme to the Dawn Theme. My collections pages were split with information above and beneath the products. Will you please share exactly how you were able to do that? I’m not sure about the split filter or the custom liquid section. My collection pages do not have subcategories.