There is a build flag related to VisionOS Simulator:
https://github.com/WebKit/WebKit/blob/main/Tools/Scripts/build-webkit#L125
After building MobileMiniBrowser.app using this flag, I found that it can run in simulator, but can't load my local build of WebKit (And I have also attempted to manually package all relevant Frameworks to MiniMobileBrowser.app,it still can‘t work).