Replace Emeralds as currency with custom item

I'm working on a mod that adds coins (Iron, Gold, Diamond, and Netherite coins) to the game. My problem is that I want villagers to trade with these coins instead of Emeralds.

Should I just set up custom loot tables and replace the vanilla ones? If yes, how would one do this (for each profession and for the Wandering Trader)? :) 

Just to clarify: I don't want to add new trades to the game. I just want to replace Emeralds as currency using my modded coins and not by just changing the Emerald texture.  

Thanks in advance :)