It looks like Bungie has decided they aren't interested in making Destiny 2 compatible with the Steam Deck..
https://help.bungie.net/hc/en-us/ar...ny-2-Steam-Guide#steam-deck-and-destiny-2-0-3
https://help.bungie.net/hc/en-us/ar...ny-2-Steam-Guide#steam-deck-and-destiny-2-0-3