Is it possible to use a glass material in a "Designed for iPad" app on Apple Vision Pro?

It's unclear how to use this example given by Apple.

class MyViewController: UIViewController {
    override var preferredContainerBackgroundStyle: UIContainerBackgroundStyle {
        return .glass
    }
}

If I try overriding the property, I get an error saying it only builds on visionOS. However, adding a compiler directive check for visionOS only returns true if the app is fully native for visionOS (no storyboards). Does this mean that UIKit enhancements are only supported for UIKit embedded in the fully native target?