Fortnite is not available natively on Steam OS, but we have you covered if you still want to play Fortnite on the Go on Steam Deck
The video above gives the best overview of all these options, but here is the short version for those wanting a quick update.
The 3 ways to play Fortnite on Steam Deck we cover are:
GeForce NOW in the Chrome Browser
Microsoft Xbox Cloud Gaming (xCloud) in the Chrome Browser
Windows 10 running on Steam Deck
GeForce NOW in Chrome
GeForce NOW is the best of the streaming options and even has a free tier for 1-hour play sessions with prices going up for their Priority and Ultimate tiers which you can see here
The only downside to GeForce NOW is that you will be mostly against PC players at is running the PC version of Fortnite.
Xbox Cloud Gaming
Typically referred to as xCloud, Xbox Cloud gaming's stream had typically been less reliable and as clear as GeForce NOW, however, this is constantly improving. This is running the Xbox Series X version of Fortnite and requires a Game Pass Ultimate subscription to play at around £11 a month.
Windows 10 on Steam Deck
If you go the windows route, we have a great guide on how to Install Windows 10 on Deck and we do recommend going with Windows 10 over Windows 11 as there are just too many problems on Deck with Windows 11.
This is the cheapest way to run Fortnite on Steam Deck in the long run, but you will need to license your copy of windows if you plan to play for more than 30 days, and also you will need half a day of your time to get up and running initially.
You will be able to run Fortnite at 60 FPS however on Windows 10 with medium settings and potentially giving you the least latency overall depending on your Wireless connection.
As Fortnite is an online-only game for the most part, it's really a matter of choice whether you want to Stream for convenience or go the full windows route, depending on the ecosystem you are already bought into.