On my macBook Pro 2019 with Intel processor, I could run apps in the visionOS simulator without any problems when I was running macOS Ventura. But since I upgraded the Mac to Sonoma, the visionOS simulator seems to be broken.
The display in Xcode sticks to "Loading visionOS 1.0", and the simulator page under "Devices and Simulators" says "No runtime".
This is independent of which Xcode version I am using. I used Xcode 15 beta2, but also tried out more recent versions.
Could it be that developing on Intel Macs was dropped on macOS Sonoma without any notice? I can see that the Xcode 15.1 specs state you need a Silicon Mac, but the Xcode 15 specs don't. And it worked for me, at least on Ventura. The "only" change I made since was upgrading the OS to Sonoma.