Categories list from queried post,post_type.php

$term_slug_list = array()

$query = new WP_Query( $args );

// loop through every product
while($query->have_posts()){
    $query->the_post();

    // get categories of product
    $product_terms = wp_get_post_terms( get_the_id(), 'product_cat');

    // check each term id with $term_slug_list
    // if this term id not in there, then push it to $term_slug_lis

    foreach($product_terms as $term){
        if(!in_array($term->slug, $term_slug_list)){
            $term_slug_list[] = $term->slug;
        }
    }
}

// make portfolio filter using the category list
<?php foreach($term_slug_list as $term):
    $term = get_term_by( 'slug', $term, 'product_cat');
?>
    <button data-filter=".product_cat-<?php echo $term->slug; ?>"><?php echo $term->name; ?></button>
<?php endforeach; ?>