shared/commonMain/UserService.kt

class UserService(private val api: UserApi, private val db: UsersDb) {
    //
}

shared/commonMain/KoinDi.kt

// called by android application
fun initKoin(appDeclaration: KoinAppDeclaration = {}) =
    startKoin {
        appDeclaration()
        modules(commonModule())
    }

// called by iOS
fun initKoin() = initKoin() {}

fun commonModule() = module {
    single<UserServiceInterface> { UserService(get(), get()) }
}

androidApp/.../UserViewModel.kt

class UserViewModel(private val userService: UserService) : ViewModel() { 
    // 
}

iosApp/.../UserViewModel.swift

class UserViewModel: ObservableObject {
    private let userService: UserService
    
    init(userService: UserService) {
        self.userService = userService
    }
}

iosApp/.../ContentView.swift

struct ContentView: View {
    @StateObject var userViewModel = UserViewModel(userService: UserService(????????))
}

Now I'm curious about the difference between using a Koin Component vs constructor injection? The docs mention this warning -

The KoinComponent interface is here to help you retrieve instances directly from Koin. Be careful, this links your class to the Koin container API. Avoid to use it on classes that you can declare in modules, and prefer constructor injection

For now I'm defining my repository using a constructor, so that android can use constuctor injection. And then I'm adding a helper class like the cheat sheet example for usage in iOS. That seems like the best of both worlds! ...though I'm not entirely sure what benefit I'm getting by still using the constructor injection in Android