I actually went on vacation the day it released. I installed it on my deck to be able to play when at the hotel. I put 14 hours in starfield on my deck. It's PLAYABLE but not really ENJOYABLE. You have to turn it down to almost the lowest setting to play it reliably.
I did not know you could play with a controller on PC. Is thist a steam customization for the deck ? (When I plug my xbox controller nothing happens in control settings or anywhere)
It is weird it doesn't work for you. I always use my Xbox controller when I play games on my pc with a very few exceptions because of the need of hot keys.
I am playing with a Xbox one controller with Bluetooth. Before did I use a Xbox 360 controller with wire until it started to not listen to me anymore (dead zone grew and dpad was always unsure what direction I clicked).
It isn't a steam thing. But steam do have configurations so you can change the layout if you wish.
For me is it plug and play but you can check out their documentation. They have a section at the bottom how you connect USB, wireless and Bluetooth.
I honestly couldn't tell you how it works. Maybe check input settings in game? The game isn't verified on deck so I wouldn't think steam has done anything specific to make the controller work.
I found it playable but being completely honest, the graphic settings are the lowest and while it looks fine enough for things nearby… shooting at enemies more than a few meters away means aiming under their name. Due to dumb circumstances making my gaming pc unavailable, I’m currently playing it “on my Mac” through GeForce Now.