paper elytra and group villager deals

So I had a great idea that was that when you trade with villagers and master them, and that is it, I think when you master a bunch of the same villagers that have the same job, they will give you a group villager, trade, say you master a bunch of brewing villagers, then they will give you a trade for example a posion and librarian villagers they will trade with you a paper elytra witch it will be a rare trade so you dont get a elytra so early and it will be a lot worse and it only can use 50 fireworks before it breaks but it will not fully break it can be reapair with paper at an anvil.