Function - Disable Checkout for some Countries and States

functions.php

<?php
/*
 * Function - Disable Checkout for some Countries and States
 */
function wc_checkout_validation() {
 
        $shipping_country     = ! empty( $_POST['shipping_country'] ) ? $_POST['shipping_country'] : $_POST['billing_country'];
        $shipping_state       = ! empty( $_POST['shipping_state'] ) ? $_POST['shipping_state'] : $_POST['billing_state'];
        
        // Add here States : More example look here -> wp-content/plugins/woocommerce/i18n/states/
        $excluded_states = array(
                'SP',
                'DF',
                'RS',
        );
        
        // Verification if you are in Brazil : More example look here -> wp-content/plugins/woocommerce/i18n/countries.php
        if ( 'BR' != $shipping_country ) {
                wc_add_notice( __( 'Desculpem-nos, infelizmente não vendemos para fora do Brasil.', 'odin' ), 'error' );
        }
      
        // Verification Brazilian States
        if ( in_array( $shipping_state, $excluded_states ) ) {
                // Here you generate State Label for your Alert, if you use a different country. Please, specific below your correct country.
                $states = WC()->countries->get_states( 'BR' );
                $state  = $states[$shipping_state];
                wc_add_notice( sprintf( __( 'Desculpem-nos, infelizmente não realizamos entregas para <strong>%s</strong>.', 'odin' ), $state ), 'error' );
        }
       
}
 
add_action( 'woocommerce_checkout_process', 'wc_checkout_validation' );