Alright. Let's assume that the new setting isn't set up such that carrying around a bunch of solidified despair gives us a major malus to social checks with everyone that matters. If that's the case, how do we break things wide open?
First things first, we can just make a ton of OP griefhax items and constantly wear them all like we're an endgame JRPG character.
We know that griefhax items can impart skill (see also our melee enhancement item), so make one of those for whatever the gimmick of the setting we're going to is. Legal skill if it's Phoenix Wright, children's card games if we're in Yugioh, etc etc.
Next, I say we make a chibi, stick it in our 4D hammerspace with all our grief, and have it enchant grief. Once there's enough enchanted grief, use it to make a second chibi. Repeat, doubling the number of chibis each time, until we have a sufficient amount of them to have the entirety of our grief supply enchanted at all times. That'll let us make any other griefhax item we want basically instantly.