Seems like a cool idea, someone remember to bring the idea up during 2022 token development.
I know I have a ton of situational tokens I keep, like Goggles of Seeing, now regularly equipping them makes me miss out on something more beneficial like +2 to hit. But it sure would be great to be able to pull them out of a Backpack of Holding or Satchel of Transference, when that rare occasion of usefulness takes place.
Again agree should not mess with the party card, but probably be a little more a slotless token, like the many thing people wear around like a bunch of horns, pouches, and scroll tubes (or it even could work a little like a hitchhiking ghost). Now you would have a bag, backpack, or satchel where you could hold extra glasses, charms or ioun stones, maybe an extra pair of pants or a shirt. Something with an effect you would like to be able to access in that corner case.
Once per game you could pull the item out and use it.
And like CJ suggested it could be something that transmutes up to higher levels that allows it to become more powerful/useful.
At the entry level maybe it would be like this:
Backpack of Holding
Stow one other token in the backpack;
free action to use this item as if equipped for rest of room (1/game)
I'm sure there are better ways to word it just want to give an idea.