onClick()

NavButton.kt

@Composable
private fun NavButton(icon: ImageVector, isSelected: Boolean = false, onClick: () -> Unit) { // <------- HERE
    val backgroundColor = if (isSelected) LightOlive else CryptoDark800
    val iconTint = if (isSelected) Color.Black else Color.White
    Icon(
        imageVector = icon,
        contentDescription = "contentDescription",
        modifier = Modifier
            .size(48.dp)
            .background(backgroundColor, CircleShape)
            .padding(10.dp)
            .clickable { onClick() }, // <------- HERE
        tint = iconTint
    )
}