Order item display: meta value filter added.
WC_Checkout class: add cart item key to 'woocommerce_add_order_item_meta' action.
Woocommerce Cart/Order Item Preambles

Can be used by extensions to add information before product titles.
This is useful in cases where product are the "values" of other
collection properties. Example: A computer is added to the cart and
"Product X" is the chosen option for a "Mainboard" category. The
preamble allows developers to add a formatted "Computer Mainboard: "
string before the product title, where 'Computer' is the name of the
Collection and 'Mainboard' is the property that this line corresponds
to.

Another alternative would be a 'parent' / 'child' organization of all
cart/order items, which in my opinion is overkill, difficult and
troublesome.