Descent: FreeSpace - The Great War Steam Deck Covered main part of functionality with using virtual menus on trackpads. Buttons A, X, Y not used so you can assign additional functionality or reassign some.
Mouse Inputs Keyboard Inputs Gamepad Inputs Touch Menus Radial Menus
Descent: Freespace Steam Deck Mappings for most of the critical functions. The game is keyboard-centric but can be adapted somewhat.
Keyboard Inputs Gamepad Inputs Touch Menus