Is it legally obligatory to purchase an apartment for the divorced woman from her deceased father's inheritance, according to his oral will, or did the will pertain to the apartment itself rather than its value after its sale?

Your father's will, stating that the apartment would be yours after his death, is a bequest to an heir, which is forbidden by Islamic law and is not effective unless the other heirs consent. This is based on the Prophet's (peace be upon him) saying: "Indeed, Allah has given every rightful person his right; so there is no bequest to an heir." If the heirs refuse to endorse the will, then the apartment belongs to all the heirs and is to be divided among them according to Islamic law. However, if the heirs ratify the will after his death, then the apartment becomes yours, and they do not have the right to sell it without your permission. If they sell it without your permission and you approve the sale, then the price belongs to you. In case of disagreement, the matter should be referred to an Islamic court or addressed by a qualified scholar capable of rendering judgment.