This Chapter pretty much confirms Yamato was stronger than Zoro in Wano and still might be. and here's why
Oda would never have anyone join the crew that's stronger than Zoro besides luffy, it'll mess with the dynamic of the crew, and we just learned that Zoro didn't even know he had Conquerors which means like Gaban said he lacks the control to use it to its full potential, Yamato did not have that problem, Yamato won't join up with the crew until Zoro masters his conquerors that basic's at the very least, that way Oda can slide her in without her overshadowing Zoro.
Zoro and Yamato are close enough in strength and skill that having Conquerors and potentially even ACOC gives her an edge
Yamato's cover story will end when Zoro masters his conquerors and she'll catch up with the crew after Elbaf.