iPhone and iPad apps will be available in the Vision Pro App Store by default
https://www.theverge.com/2023/9/5/23860335/apple-iphone-ipad-apps-vision-pro-app-store-default
The visionOS App Store is coming to developers this fall.
This sounds to me like there won’t be a checkbox to disable iPad/iOS Apps on Vision Pro like there is for macOS.
Edit: there is a checkbox (╯°□°)╯︵ ┻━┻