The United Planets with it's dozens of worlds, is Wakanda x Infinity already!
Plus they live in Metropolis, a fictional city, on a 'united' Earth, which is pretty much a fictional country of it's own (that picks it's President by computer!).
Isn't that Marzal Island? Its technology developed independently from the rest of Earth, but when Dawnstar and Shadow Lass visited, it appeared equally as advanced as 3Oth-century Metropolis, if not moreso.
“I'm not crazy about reality, but it's still the only place to get a decent meal.” -- Groucho Marx