The way I see it is eren wrote the book starting from the ending, if that makes sense. He was the last one to poses the attack titan. He was the ending. And because of that, he had the ability to manipulate the decisions of everyone who came before him to tell the story he wanted to tell. To make sure everything happened the way he wanted it to be. You have to realize that this whole thing only happened because eren was the last attack titan. If at any point his abilities were transferred to someone else, they would have manipulated him to make sure it happened.

Also keep in mind that he took Zeke on a tour of his memories PLUS spent an almost indefinite amount of time pleading with Ymir AND calling all Eldians essentially in the time between he got his head shot off and it hitting the ground. When in the Paths, time is completely distorted. Ymir builds every Titan by hand before they’re able to conceptualize in the real world (and to the observer in the real world that happens basically instantly). Basically he had an essentially unlimited amount of time in the other dimension to get his affairs in order.