Since the launch of the original Vision Pro, the iPad version of Steam Link has been available on visionOS through the App Store. While this allowed for easily playing your flatscreen Steam library in the headset, it limited you to having a window with the 4:3 aspect ratio of an iPad, yet streaming the wider aspect ratio of your PC, leading to black bars on the top and bottom of the window – something entirely unnecessary in XR.
The iPad app also limited the window's resolution to that of an iPad, around 2732×1537 for 16:9 content.
With the visionOS app, released on the App Store a few weeks ago, the Steam Link window supports up to 4K streaming resolution, dynamically matches the aspect ratio of the PC you're streaming from, and lets you adjust the curvature of the window to your liking.