Title speaks for itself. Considering you're the person who made Construct's Armory, maybe this would be easier for you?

This likely won't end up as part of Colytra. You can already attach elytras normally to Construct's Armory chestplates with Colytra so having a modifier would be strictly worse. I will probably make this into a small add-on mod to Construct's Armory for 1.14.4+, partially to isolate the dependency on Caelus.