CurrencyFormat.kt

fun moneyFilter(text: AnnotatedString): TransformedText {
    return TransformedText(
        text = AnnotatedString(text.text.toLongOrNull()?.formatWithComma() ?: ""),
        offsetMapping = object : OffsetMapping {
            override fun originalToTransformed(offset: Int): Int {
                return text.text.toLongOrNull()?.formatWithComma()?.length ?: 0
            }

            override fun transformedToOriginal(offset: Int): Int {
                return text.length
            }
        }
    )
}

fun Long.formatWithComma(): String =
    NumberFormat.getNumberInstance(Locale.US).format(this ?: 0)
    
TextField(
        value = amountState.value,
        onValueChange = {
                // change state
        }
        keyboardOptions = KeyboardOptions(keyboardType = KeyboardType.Number),
        visualTransformation = {
                  moneyFilter(it)
        }
     )