@EnvironmentObject.swift

class Order: ObservableObject {
    @Published var items = [MenuItem]()
}

class SceneDelegate: UIResponder, UIWindowSceneDelegate {
    var window: UIWindow?
    var order = Order()

    func scene(_ scene: UIScene, willConnectTo session: UISceneSession, options connectionOptions: UIScene.ConnectionOptions) {
        ...
        let contentView = AppView().environmentObject(order) // Setting order in environment of AppView() which is TabView in my case.
        ...
    }
  
}

struct CheckoutView: View { // CheckoutView is one of the tab in TabView. Child view of AppView. So CheckoutView can access saved order from parent's environment
    @EnvironmentObject var order: Order
}