Actually i work on UE4.21, i worked also on rpg for a small game on xbox one.
carry a game on another platform can be pretty hard except if low level of the engine can use multiple or different SDK / langage (ex: xbox one, w10 => uwp).
I read the old code from WAR Z, he was done with an old visual studio, with old technologies. ( vfx, gfx, collider, IA, shadow, ray simulation etc all is old.)
And i think, no, I'm 100% sure New Z is the same " engine " and he's really not friendly to code in, cause he was full bugged at the original format.
For Sony you can forgot, they need an Hard contract to do a carry on PS4. ( Nintendo => Same and more strict.)
For Xbox it's possible, i've made it last year, more than they make a convention from UWP wo can run on window 10 and xbox one, since 2 years ago, Microsoft offer a " free xbox one sdk "
you don't need anything, but you need to swap c++ to uwp more than without the full payed contract you have only 2 go of ram and 1 of 8 CPU core.
PS: no i can't help here,
I already asked, but they refuse.