"Nearly half" of all Nintendo Switch consoles have Epic Games' Fortnite Battle Royale downloaded on it. A testament to how popular the battle royale game is.
There have been over 22 million Nintendo Switch units sold so far, so the fact that half of those consoles have Fortnite downloaded on them is no small feat. The Legend of Zelda: Breath of the Wild for example hit 10 million sales, though of course price is a factor since Fortnite is free. Since 2017 Fortnite has been downloaded 125 million times, and playercounts have hit 80 million.
Like on other consoles Fortnite is free-to-play on the Nintendo Switch. Cross-platform play is available as well making the Switch a perfectly viable system to play Fortnite on. A popular game on a popular console is a win-win for everyone in this situation.
In Nintendo's latest financial report for the quarter the company announced that the Switch surpassed the lifetime sales of the GameCube, after previously beating out the Wii U. While it'll take some time to reach the monumental heights of the Wii, Nintendo appears to be confident in the Switch heading into the holiday season.