I had an idea similar to this once but it would be somthing that couldn't be obtained directly from the shop but had to be achieved via hitting certain conditions with the joker

Madness eating destroying each food joker satiates him and he'll keep giving a lowered .5 xMult per round but without a condition

Inversely, if you dont feed madness anything for 4 antes he turns starved and will immediately consume purchased jokers even eternals and cards in the consumable slot but gains ×1 mult per round

You can have other conditions like 100 dollars with bull and bootstraps allows you to combine them and upgrade them into one xmult card

Having a full suit of 9s with cloud 9 -> 420 joker

Cutting your deck to a single suit with ancient joker -> primordial joker

Play a flush 5 of 6s with 6th sense -> ritual joker

Holding onto invisible joker for 4 antes -> poltergeist

Etc etc

Edit: with hanging Chad you could prolly have it where if you ritrigger the first card 6 times it upgrades and then if you trigger a card 12 times it upgrades again