Get WordPress Terms Nested Array

WP_Terms_Nested.php

<?php

if (!class_exists('WP_Terms_Nested')) {

    class WP_Terms_Nested
    {

        public static function get($arg = []): array
        {

            // @see https://developer.wordpress.org/reference/classes/wp_term_query/__construct/
            $defaults = [
                'taxonomy' => 'product_cat',
                'order' => 'ASC',
                'hide_empty' => true,
                'fields' => 'all',
                'parent' => 0
            ];
            $args = wp_parse_args($arg, $defaults);

            // Get Terms
            $terms = get_terms($args);

            // Sort children
            $sorted_terms = [];
            self::sort($terms, $sorted_terms);

            // return data
            return $sorted_terms;
        }

        public static function sort(array &$terms, array &$into, $parent_id = 0)
        {
            foreach ($terms as $i => $term) {
                if ($term->parent == $parent_id) {
                    $into[$term->term_id] = $term;
                    unset($terms[$i]);
                }
            }

            foreach ($into as $top_term) {
                $top_term->children = [];
                self::sort($terms, $top_term->children, $top_term->term_id);
            }
        }
    }
}

Example:

$terms = WP_Terms_Nested::get([
    'taxonomy' => 'product_cat',
    'parent' => 0,
    'orderby' => 'count'
]);
foreach ($terms as $term) {

    // Check is Nested
    if(isset($term->children) and !empty($term->children)) {
        
    }
}