Jetpack Compose: How good is having a separate ViewModel for every interactive component on Screen

I have chat like interface in Jetpack compose. Every message can either be Text, Audio, Video, or Image.

Each Audio message is displayed with the help of a AudioPlayer composable, and an attached controller to it. The screen ViewModel has a single instance of AudioPlayerController, and each component collects its state from that controller's StateFlow<UiState>. UiState contains states like audioFilePath, fileName, duration, progress, etc. I'm determining which player of the state is playing based on the filePath.

@Composable
fun AudioPlayerUi(audioFilePath:String, ...) {
  val uiState by controller.uiState.collectAsState()
  val isPlaying by remember { derivedStateOf { audioFilePath == uiState.audioFilePath } }
  ...
}

And there are many more components on the screen which have similar logic.

My question is how good is it if my controller extends ViewModel and I create an instance of that controller in each component?

@Composable
fun AudioPlayerUi(audioFilePath:String, ...) {
  val controller by viewModel<AudioPlayerController>()
  val uiState by controller.uiState.collectAsState()
  val isPlaying = uiState.isPlaying
  ...
}

Now there are more questions following it.

• How good is this approach
• Memory concerns, since there is a viewModel instance for each component, what about the components which are not visible on the screen. Do their viewModels still live in the memory?

My Scrren is something like:

ReceivedText
ReceivedAudio
             SentText
             SentAudio
             SentImage
ReceivedImage
              SentText
ReceivedAudio
ReceivedImage
             SentAudio
             SentImage

##### INPUT WIDGETS ##### 
##### Can be any one ####
TestInput, AudioRecorder, 
Camera, etc
#########################

Each sent component has editing feature as well.

I read most articles and documentations available online, but none of them mentions about having each component having it's vieeModel. Also I can't have all the logic in screen ViewModel because each controller is big in itself.

You could certainly do that but what are the benefits. Are you caring about orientation changes, process death or having your ViewModel scoped to the parent Navbackstackentry?
I think is simpler just having an AudioPlayerUiState class and just use

val controller = remember {
 AudioPlayerUiState(initialValuesFromViewModel) 
}

ViewModel is just State or the term I see often, "StateController", because it actually emit State updates. Anyway, ViewModel has especial treatment, it survivives config changes, process deaths and is nicely scope to backstack entries, or Activity. If you don't need any of those then just create a State/StateController class to your Composables and scope it to the composable with remember or remember (key)

This is an opinion-based question.
(So the answer is aligned with the opinions of Android team recommendations)

To give an answer from Android Docs,
Reference - https://developer.android.com/jetpack/compose/state-hoisting#screen-ui-state

Use ViewModel as a screen UI state holder.

Using ViewModel for each component does not have any additional benefits and it is an additional overhead.

The following issues can happen,

1. Issues in inter-component data sharing.
2. More memory usage.
3. Lifecycle issues. (As already mentioned in the question, what UI is visible, what is hidden, init can happen way earlier for some components, etc).

For individual components, you can use a simple class as a StateHolder or move to a screen-level ViewModel if required to use business logic.

How to choose State Holder in a simple way.

1. Screen level state involving business logic - ViewModel
2. Component level state involving business logic - Hoist to ViewModel
3. Any UI-specific state - Simple class as state holder or within Composables.

To add on, as mentioned in the starting, this is an opinionated question and hence an opinionated answer. You can use ViewModel for the Component level if you see it is required and you are careful to handle all the issues related to it.