Ordering Structure Sections with Structure Handles
Use SuperSort or write your own Twig filter for it. Craft/Twig don't come with a sort filter to sort by key and replicating the functionality  (storing array keys, nested loops) is possible but kind of messy and also not performing as well.

I can understand the desire to not be reliant on too many plugin, but the functionality you need from SuperSort is simply a wrapper for a PHP function, so you can easily swap it out for another plugin if ever necessary.

It is also a great opportunity to start looking into plugin dev, write your first Twig extension or a simple Template Variable might just do it.