Ya, it’s not an option with the steam link settings for some reason???
Just open SteamVR without a headset connected and them go to your SteamVR settings/openxr and choose SteamVR as your OpenXR default. This then worked fine for me, including other apps like Hubris that requires OpenXR. If you go back to Link or Air Link you’ll need to select the Oculus OpenXR default again. Maybe Steam will make this all happen automatically in the future, like VD currently does.
Pretty early days with this app but I’m already seeing some nice results with it. Very comparable to what I can get with Air Link or VD. I still need to finetune this a bit more but when I do I’ll post my settings.