best method for obtaining custom loot on multiplayer server

So, I want to add more heads, and maybe more like a quest to find them to the datapack There were a few ways I was thinking about it not sure what would be best practice/more fun. I original thought I had the thought that general mining would spawn a custom currency you can use with a wondering trader to buy heads. And I’m happy with that for some things but not all 80 unique heads. But I was thinking it would be cool to find a structure maybe a small shrine or Torii gate. But I don’t want them to be abundant and I don’t want the collectables to be so rare that others on the server can’t get them either How would you achieve this. One thing I was thinking was maybe have 4-5 structures spawn per dimension and when you discover one it maybe disappears or gets replaced with a different structure like a ruined version. And then another one gets spawned in a random location within a few thousand blocks. Not sure what would be the best way to do it. I thought about adding it to vanilla chests like villages, monuments cities bastions ect ect, but my concern is that other packs/mods will override the contents and they won’t appear in any. So I'm thinking biome specific small structures/features that you find. like these swords, with a chest underneath them. but i'm not sure if they should drop a currency or a way to summon a wondering trader