Can I replace produceState with mutableStateOf in the Compose sample project?

The following Code A is from the project.

1. uiState is created by the delegate produceState, can I use mutableStateOf instead of produceState? If so, how can I write code?

2. Why can't I use Code B in the project?

Code A

@Composable
fun DetailsScreen(
    onErrorLoading: () -> Unit,
    modifier: Modifier = Modifier,
    viewModel: DetailsViewModel = viewModel()
) {
    val uiState by produceState(initialValue = DetailsUiState(isLoading = true)) {
        val cityDetailsResult = viewModel.cityDetails
        value = if (cityDetailsResult is Result.Success<ExploreModel>) {
            DetailsUiState(cityDetailsResult.data)
        } else {
            DetailsUiState(throwError = true)
        }
    }
   when {
         uiState.cityDetails != null -> {
    ...
}


@HiltViewModel
class DetailsViewModel @Inject constructor(
    private val destinationsRepository: DestinationsRepository,
    savedStateHandle: SavedStateHandle
) : ViewModel() {

    private val cityName = savedStateHandle.get<String>(KEY_ARG_DETAILS_CITY_NAME)!!

    val cityDetails: Result<ExploreModel>
        get() {
            val destination = destinationsRepository.getDestination(cityName)
            return if (destination != null) {
                Result.Success(destination)
            } else {
                Result.Error(IllegalArgumentException("City doesn't exist"))
            }
        }
}


data class DetailsUiState(
    val cityDetails: ExploreModel? = null,
    val isLoading: Boolean = false,
    val throwError: Boolean = false
)

Code B

@Composable
fun DetailsScreen(
    onErrorLoading: () -> Unit,
    modifier: Modifier = Modifier,
    viewModel: DetailsViewModel = viewModel()
) {

    val cityDetailsResult = viewModel.cityDetails
    val uiState=if (cityDetailsResult is Result.Success<ExploreModel>) {
        DetailsUiState(cityDetailsResult.data)
    } else {
        DetailsUiState(throwError = true)
    }

    ...

from Can I replace produceState with mutableStateOf in the Compose sample project?