SwiftUI: .fullscreenCover doesn't show .navigationTitle

Since NavigationView has been deprecated, what is the new way to show the navigation bar with a navigation title in SwiftUI? The code below doesn't show the nav bar:

var body: some View {
    Button {
        showFullscreenModal.toggle()
    } label: {
        Text("Test Fullscreen")
    }.sheet(isPresented: $showFullscreenModal) {
        Text("Modal content").navigationTitle("Modal title").toolbar {
            Button {
                self.showFullscreenModal = false
            } label: {
                Text("Cancel")
            }
        }
    }
}

Am I doing something wrong?