So, there’s relationships/order to let you order your list of categories on the client, but no way I can find to do that from the portal except tweaking the category names until they hit the right order alphabetically.
And you can arrange your relationships within a category non-alphabetically using the Order field on the portal, but on the client, they still come up in alphabetical order.
It’d be cool if categories could be ordered on the portal, and if the client honoured the portal’s relationship-order!