WooCommerce - Collect buyers First and Last Name at Registration

functions.php

/* BEGIN REGISTRATION FIELDS */
function cs_wc_extra_register_fields() {
        ?>
        <p class="form-row form-row-first">
                <label for="reg_billing_first_name"><?php _e( 'First Name', 'textdomain' ); ?> <span class="required">*</span></label>
                <input type="text" class="input-text" name="billing_first_name" id="reg_billing_first_name" value="<?php if ( ! empty( $_POST['billing_first_name'] ) ) esc_attr_e( $_POST['billing_first_name'] ); ?>" />
        </p>
        <p class="form-row form-row-last">
                <label for="reg_billing_last_name"><?php _e( 'Last Name', 'textdomain' ); ?> <span class="required">*</span></label>
                <input type="text" class="input-text" name="billing_last_name" id="reg_billing_last_name" value="<?php if ( ! empty( $_POST['billing_last_name'] ) ) esc_attr_e( $_POST['billing_last_name'] ); ?>" />
        </p>
        <?php
}
add_action( 'woocommerce_register_form_start', 'cs_wc_extra_register_fields' );
function cs_wc_validate_extra_register_fields( $username, $email, $validation_errors ) {
        if ( isset( $_POST['billing_first_name'] ) && empty( $_POST['billing_first_name'] ) ) {
                $validation_errors->add( 'billing_first_name_error', __( '<strong>Error</strong>: Required.', 'textdomain' ) );
        }

        if ( isset( $_POST['billing_last_name'] ) && empty( $_POST['billing_last_name'] ) ) {
                $validation_errors->add( 'billing_last_name_error', __( '<strong>Error</strong>: Required.', 'textdomain' ) );
        }
}
add_action( 'woocommerce_register_post', 'cs_wc_validate_extra_register_fields', 10, 3 );
function cs_wc_save_extra_register_fields( $customer_id ) {
        if ( isset( $_POST['billing_first_name'] ) ) {
                update_user_meta( $customer_id, 'first_name', sanitize_text_field( $_POST['billing_first_name'] ) );
                update_user_meta( $customer_id, 'billing_first_name', sanitize_text_field( $_POST['billing_first_name'] ) );
        }
        if ( isset( $_POST['billing_last_name'] ) ) {
                update_user_meta( $customer_id, 'last_name', sanitize_text_field( $_POST['billing_last_name'] ) );
                update_user_meta( $customer_id, 'billing_last_name', sanitize_text_field( $_POST['billing_last_name'] ) );
        }
}
add_action( 'woocommerce_created_customer', 'cs_wc_save_extra_register_fields' );
/* END REGISTRATION FIELDS */