Steam Deck OS / Linux - Mouse is not in the game

My friend is stuck on the Gift Screen every time he opens the game. He's never played the game before, and he is on Steam Deck OS, but his computer is functionally a linux. His mouse is not in the game, he can't press play online or play offline, then his mouse won't work for opening the gift. He hasn't had a game with this issue either. He's trying 64 and 32 bit, unable to actually play the game. He uninstalled, restarted his PC, verified game files, nothing.

SOLVED!!!! - Steam Deck OS automatically makes you use controller, even if you don't want to.