Adding back-in-stock to WooCommerce collection page

add_action('woocommerce_after_shop_loop_item', 'render_onvoard_back_in_stock_collection_link');

function render_onvoard_back_in_stock_collection_link() {
  global $product;

  // generate product json
  $product_id = $product->get_id();
  $variation_ids = array();
  $variations_data = array();

  if ($product->get_type() === "variable") {
    $variation_ids = $product->get_children();
  }

  foreach($variation_ids as $variation_id) {
    $variation = wc_get_product($variation_id);
    if (empty($variation) || !$variation) {
      continue;
    };

    $variation_data = array(
      'id' => $variation->get_id(),
      'name' => implode(" / ", $variation->get_variation_attributes()), // https://wordpress.stackexchange.com/a/343091
      'sku' => $variation->get_sku(),
      'status' => $variation->get_status(),
      'manage_stock' => $variation->get_manage_stock(),
      'stock_quantity' => $variation->get_stock_quantity(),
      'stock_status' => $variation->get_stock_status(),
    );

    array_push($variations_data, $variation_data);
  }

  $product_data = array(
    'id' => $product->get_id(),
    'name' => $product->get_name(),
    'type' => $product->get_type(),
    'sku' => $product->get_sku(),
    'status' => $product->get_status(),
    'manage_stock' => $product->get_manage_stock(),
    'stock_quantity' => $product->get_stock_quantity(),
    'stock_status' => $product->get_stock_status(),
    'variations' => $variations_data,
  );

  if ($product_data['stock_status'] !== 'outofstock') {
    return;
  }

  $product_json = htmlspecialchars(json_encode($product_data), ENT_QUOTES, 'UTF-8');
  ?>
   <div class="ov-bis-notify" style="margin-top: 5px; margin-bottom: 15px;">
    <a href="#"
    class="ov-bis-trigger"
    data-woocommerce-product="<?php echo $product_json; ?>"
    style="font-size: 13px; color: #6d7390;"
    >
     Notify me when available
    </a>
   </div>
  <?php
}