In Desktop Mode, I have a modified controller configuration for my Deck that lets me move the mouse with the thumbstick, click with the triggers and press enter with the A button. Once this does, navigate down to Switch to Desktop and click it.
Download the EmuDeck installer using the Steam Deck browser. The same can be done in the process profile individually. Add Xenia Canary as a Non-Steam Game on Your Steam Deck.
Steam deck emulate xbox controller Type 'install-interception.
