New hardest advancement idea

Kinda ridicolous, but hear me out: an idea for an advancement possibly harder than How Did We Get Here.

Master Zookeper: have simultaneously on a lead one of every mob that can be leashed.

Imagine collecting all the different mobs from all biomes in one place without anything killing them and also preventing them from killing each other. Also, some sort of chunk loaders and time circuits would be necessary to bring a hoglin from Nether and leashing it before it zombifies.

I think this is absurdly difficult but I don't see a reason why it would be impossible, seems like a good challenge for players that mastered HDWGH and all normal advancements.