Emporio isn't an unknown element, but he made it through the universe reset alive, anyone who was alive when the universe reset as a result of Pucci's death hypothetically makes it to the next universe with their spirit intact, assuming the new universe that was created as a result of Pucci's death follows the same rules as in this image, even if it's a completely different timeline, which dictates that anyone dead does not make it to the new universe, but there is still a counterpart of them in the new universe. And, as I said, anyone alive when it resets retains their experiences and makes it to the new universe while replacing the "them" that was created.
There have been no stories in the universe created by Pucci's death to corroborate this theory, though, as it's obvious from the Joestar family tree in Jojolion that Irene doesn't exist, and that the SBRverse is different.
I just assumed that Jojolion takes place before Irene is born.