This page is our investigation of cross-play feature in game called Fortnite. We also want to mention that - we always put manual efforts to find the precise, valid, and what is more important official information about different game features without using AI.
Games can have different cross-play combinations, for example the game can have cross-play between PC, Playstation 5, Xbox X|S, but not between old generations like: Xbox One, Playstation 4, PC. To avoid any misinterpretations, we group them into so called "cross-play variations".
Any store inside the cross-play variation have a cross-play only with a store in the SAME variation. We also want to notice, that we put into variation not platform, but store + platform. That is required because some games, for example, can have cross-play between a Playstation 5 and Steam, but not Playstation 5 and Epic Games.
Fortnite didn't have cross-play support at the release, but it was added soon after approval from Sony, and covered in a PlayStation Blog article here. The article directly specifies that Fortnite received full cross-play support between PlayStation, Xbox, PC via Epic Games Store, Android, and IOS.
We can also find the cross-play information on the official Fortnite FAQ page here, which says the same things.
It is also important to mention that, per the FAQ, to play Fortnite in cross-play mode, you have to create an Epic Games account, but this is a common practice that is used by most cross-play games.