This worked:

@Composable()
fun IconImage(modifier: GlanceModifier = GlanceModifier) {
    val assetPath : String = "assets/test.png"
    val loader = FlutterInjector.instance().flutterLoader()
    val assetLookupKey = loader.getLookupKeyForAsset(assetPath)
    val inputStream: InputStream = LocalContext.current.assets.open(assetLookupKey)
    val bitmap = BitmapFactory.decodeStream(inputStream)
    Image(
      ImageProvider(bitmap), modifier = modifier, contentDescription = null
    )
}