I do. I just downloaded XIVLauncher from the discovery store in desktop mode, added it as a non steam app and then run it in game mode. It downloads FFXIV on its own and manages its own Wine prefix for it.

Yup, literally go to desktop and go to Discovery app that comes pre installed, type in ffxiv and it should pull it right up. Just have to go to steam and add non-steam game and you’ll have it when you’re in the deck environment.