https://www.gamespot.com/articles/e3-2018-fortnites-new-switch-version-offers-everyt/1100-6459800/

The battle royale juggernaut Fortnite expanded its reach further by launching on Nintendo Switch soon after it was officially announced during Nintendo's E3 presentation. It's free on the Eshop and has all the features of the PlayStation 4, Xbox One, and PC versions (except for the co-op Save the World mode--it's Battle Royale only). Fortnite on Switch lives within the same ecosystem as all other versions; as soon as you hop in, Season 4 and the current weekly challenges are live. The Battle Pass is available, and grouping up in parties works the same.

Although you can link your Epic account to the Switch version if you've been playing on PC, Xbox One, or mobile to keep working on your progress, PS4 players are left in the dust. Sony is blocking user from linking accounts cross-platform, which also means there's no cross-play between these platforms. This says more about Sony than it does about Nintendo, but it's something long-time PS4 players should know, as well as those hoping to play with their PS4-having friends.