PROTON_HIDE_NVIDIA_GPU=0 PROTON_ENABLE_NVAPI=1 gamemoderun %command%
The game seems to run without any issues under Proton-GE. Haven't tried vanilla Proton, and the launch options are optional. I've played for the first hour or two, and the game is gorgeous. It detects my XB1S controller as it should, and I've had no problems playing whatsoever.
gamemoderun %command%
There was a problem where when I used a controller I could not equip certain boons without using the mouse to do so. Easily worked around by using the mouse briefly then returning to using the controller.
Game runs fantastic just like it would on windows under Linux Mint 21.2 with no tinkering required. Only a small problem in the menus here and there where you sometimes have to use a mouse instead of a controller. Easily worked around and not even sure if it's a Linux specific issue.
Go into Propertiesand set the internal and external display resolution to 1280x720
It appears to be capped at 60fps so if you have an OLED Deck set the display to 60Hz (or lower)
By default the game renders at 16:9 but crops itself to 16:10 to fit the display. This results in text boxes being cut off at the sides of the screen. Setting the resolution as above seems to fix it by forcing a 16:9 AR.
I just tried the demo and was flawless, it works perfectly. This game is made to play with a controller but it's possible to play it using keyboard.