As reported by engadget,
All of these characters are exclusive to their respective platforms, but they do have one thing in common. They’re part of titles that have just come out (in the case of The Mandalorian) or are due to be released soon, like the delayed Halo Infinite (exclusive to the Xbox Series X) and God of War which is set to hit the PS5 in 2021. To that end, they’d help Sony and Microsoft promote these games and keep users excited about them.
All of this is good news for Fortnite players, as they essentially get to play with a mix of characters from different universes, like in some old-school DC/Marvel crossover. You can get the Kratos skin or bundle now, and if you’re matchmaking from a PlayStation 5, you’ll also unlock the Armored Kratos Style bonus skin.