@State with type @observable

gistfile1.swift

@main
struct SomeApp: App {

    @State var path: [Int] = []

    var body: some Scene {
        return WindowGroup {
            NavigationStack(path: $path) {
                Button("Push") {
                    path.append(1)
                }.navigationDestination(for: Int.self) { _ in
                    SomeView()
                }
            }
        }
    }
}

@Observable
class SomeManager {
    init () {
        print("Manager init")
    }
    
    deinit {
        print("Manager deinit")
    }
    
    var test = "Hello"
}

struct SomeView: View {
    
    @State var manager = SomeManager()
    
    init() {
        print("Some view init")
    }
    
    var body: some View {
        Button(manager.test) {
            manager.test = UUID().uuidString
        }
        
    }
}

// Tapping the "Push" button outputs
// Manager init
// Some view init

// Tapping "Test" replaces text with UUID string

// Tapping back:
// Manager deinit