Fortnite on Apple TV
If they’ve already ported Fortnite to iOS, why haven’t they ported it to Apple TV? That should be easy. The obvious answer: Apple TV is such a non-entity for gaming that Epic doesn’t even consider a relatively easy port to be worth their time.
There is another reason: Apple TV 4th generation is not powerful enough to drive this game. It has the A8 SoC chip, which isn't supported by the Fortnite on iOS. Only the 5th gen is fast enough.