In my kimchi, I recently added apples and algae to my traditionnal ginger, pepper and garlic seasoning and it was really good! I want to try squash kimchi soon... I know some use sticky rice
water and fish too but I never tried it yet.
It also kind of make sense that you can't find the same taste when not in Korea or Japan since it is so dependant on the conditions in which it is made and the wild bacterias that are present. The kimchi equivalent I tasted in China were so specific, I wouldn't know where to begin to replicate them!
Kimchi and other ferments are such an amazing world of possibilities!