Include only certain products on the KuantoKusta WooCommerce feed

include_kk_categories.php

<?php
//Get the plugin from https://www.webdados.pt/wordpress/plugins/feed-kuantokusta-para-woocommerce/
add_filter( 'kuantokusta_product_node_show', 'my_include_kk_categories', 10, 2 );
add_filter( 'kuantokusta_variation_node_show', 'my_include_kk_categories', 10, 2 );
function include_kk_categories( $show, $product ) {
	//If not show, we don't neeed to process the item
	if ( $show ) {
		//Init as false
		$show = false;
		//Product categories IDs to include in the feed
		$categories_to_include = array(
			333,
			336,
		);
		//Has at least one category? Return true
		if ( has_term( $categories_to_include, 'product_cat', $product->get_id() ) ) return true;
	}
	//Return
	return $show;
}