Epic won’t update Fortnite to run on the Steam Deck. Tim Sweeney says Linux is ‘a terrifically hard audience to serve’ (2022)
Epic won’t update Fortnite to run on the Steam Deck
https://www.theverge.com/2022/2/8/22923163/fortnite-steam-deck-update-epic-tim-sweeney
But you can always install Windows.