I originally thought he was going to show up, we've seen him a couple times, invading Teach and in the fb fighting Kaido, I also thought the whole narrative of The Death Coming for Orochi But as of right now, its just too late, and there really are no signs pointing to his presence. Its not only that he would have to cross thru the Charlottes/WG grand fleet, and enter the natural defenses of Wano, but ALSO, he would have to know where the battle is happening, which heck, not even the Wano-kunians know about it, and lets not even talk about how he would get up there
Moria doesn't need to know the specific location, only the country. And he knows where the battle is taking place as of this moment, courtesy of Blackbeard who fed him the details. How's he going to get there, you ask? If he's coming along the Blackbeard pirates you can be damn sure he'll make it. The WG fleet and the Big Mom pirates won't even be a problem.
Its just better to end the battle now, stretching it will only make things much less satisfying.
Sorry, but that ain't how things work.
Oda is the writer of this story. Oda's the one that decides when it ends. For almost a decade Oda had been talking about Wano, and how the aftermath of it would shake the very foundations of the world. If there's an arc he had plenty of time to plan out thoroughly is that one.
This is the last time I've said this.