My idea is that this could be done 1 or 2 ways. An old item, from a battle pass or old season is brought into the shop, sold for its amount, kinda like the red crow seasonals. Another way could be, you get few tickets, let's says 3, you are allowed to use those tickets to buy any previous item that has ever been sold on the game. This idea goes for battle pass or normal purchasable cosmetics.

I think that if ubi were to allow certain battle pass items to sold in the item shop, similar to how they brought back the seasonal skins from red crow, I think this because it's fair for people who didn't have the chance to.