Pretty much all the 1st party stuff was a surprise (a new 2D Zelda starring Zelda had been rumored/teased by PapaGenos a few weeks earlier; he also said Prime 4 was targeting Fall 2024 and would show up at the direct, so kinda half credit I guess?). One person had claimed back in May that a Mario&Luigi game was in development and could get announced this fiscal year, but nobody really believed it and definitely nobody was expecting it to show up here
I think the only 3rd party stuff that leaked was Among Us, Fantasian, Darkest Dungeon 2, and I guess kinda the Dragon Quest stuff (a couple leakers had claimed it would be the whole trilogy in one game and that it'd show up at the direct; we got DQ3 and DQ1+2 as separate games, but it was at the direct). Pyoro also did one of those "random emojis teasing at a game" thing that turned out to be for My Summer Adventure, which was only in the Japanese version of the direct. So most 3rd party stuff also wasn't leaked