Is zakat obligatory on the two million riyals waived from the debt, and on the other amounts allocated for debt repayment, which have not yet been paid due to incomplete creditor documentation?

There is no Zakat due on the heirs for the amount allocated to pay off the deceased's debt, because it belongs to the creditors and has not reached the heirs. Similarly, there is no Zakat on the shares of the inheritance that the heirs have not yet received. As for the creditors, there is a difference of opinion regarding their Zakat; some scholars hold that Zakat becomes obligatory on it after it is received and a full year has passed.