I had an odd idea that seemed so obvious recently that I wanted to ask about it. Has anyone tried making a dry cider, then adding a soda extract (like ginger beer or orange soda) and back sweetening it at kegging? Essentially using a dry cider as a soda base instead of water? It just seems so obvious, but I haven’t encountered it anywhere. With a ginger beer, it might even be worth back sweetening with apple juice concentrate, since apple and ginger already taste good together.
Sounds like a great idea, run with it. It might be your own invention.