Remove Selected Checkout Fields with Woocommerce Depending on Shipping Method Redux - wordpress

Question

In reference to this Remove selected checkout fields with woocommerce depending on shipping method
How can I adapt the codes in order remove different fields based on different shipping methods selected?
I've tried modifying the beginnging part to below, but it just stops working...
add_filter( 'woocommerce_checkout_fields', 'xa_remove_billing_checkout_fields' );
function xa_remove_billing_checkout_fields( $fields ) {
$chosen_methods = WC()->session->get( 'chosen_shipping_methods' );
// uncomment below line and reload checkout page to check current $chosen_methods
// print_r($chosen_methods);
$chosen_shipping = $chosen_methods[0];
if ($chosen_shipping == 'flat_rate:13') {
$shipping_method = 'flat_rate:13';
$hide_fields = array( 'billing_address_2', 'billing_city', 'billing_state', 'billing_postcode' );
}
if ($chosen_shipping =='flat_rate:7') {
$shipping_method = 'flat_rate:7';
$hide_fields = array( 'billing_city', 'billing_state', 'billing_postcode' );
}
foreach($hide_fields as $field ) {
if ($chosen_shipping == $shipping_method) {
$fields['billing'][$field]['required'] = false;
$fields['billing'][$field]['class'][] = 'hide';
}
$fields['billing'][$field]['class'][] = 'billing-dynamic';
}
return $fields;
}
The other part looks like this, which I copied and modified from another answer
add_action( 'wp_footer', 'cart_update_script', 999 );
function cart_update_script() {
if (is_checkout()) :
?>
<style>
.hide {display: none!important;}
</style>
<script>
jQuery( function( $ ) {
// woocommerce_params is required to continue, ensure the object exists
if ( typeof woocommerce_params === 'undefined' ) {
return false;
}
var show = ['flar_rate:7', 'flat_rate:13'];
$(document).on( 'change', '#shipping_method input[type="radio"]', function() {
// console.log($.inArray($(this).val(), show));
if ($.inArray($(this).val(), show) > -1) { // >-1 if found in array
$('.billing-dynamic').removeClass('hide');
// console.log('show');
} else {
$('.billing-dynamic').addClass('hide');
// console.log('hide');
}
});
});
</script>
<?php
endif;
}
Also, if I change the country, which changes also the shipping zone, the fields ain't reverted until I select the shipping method again.
Thanks in advance.