I think it's silly to argue that Oz wouldn't be a sizable get as a theme park land. It's not Potter or Pokemon-tier, but few IP truly are.
Oz makes at least as much sense as a Zelda, Avatar, or UCM land. It's practically the most timeless property there is. It doesn't immediately translate into rides or in-universe merch as well as some other picks, but we've definitely seen stranger IP's get utilized in those ways.
I think it would work best as a land built into a park on opening day, like Universal Great Britain, opposed to an expansion somewhere like Epic Universe. I feel it shares a very similar cultural spot as Dark Universe, which would also be a pretty hard sell as an expansion to an existing park imo.