Magento Analytics Integration

// Magento injects tracking via layout XML and observer classes rather
// than simple hooks. Conceptual structure (shown as commented reference,
// actual implementation is PHP/XML within a custom module):

/*
// In a custom module's events.xml:
<event name="sales_order_place_after">
    <observer name="ga4_purchase_tracking"
               instance="Vendor\Ga4Tracking\Observer\TrackPurchase" />
</event>

// In the Observer class:
public function execute(Observer $observer) {
    $order = $observer->getEvent()->getOrder();
    $items = [];
    foreach ($order->getAllVisibleItems() as $item) {
        $items[] = [
            'item_id'   => $item->getSku(),
            'item_name' => $item->getName(),
            'price'     => (float) $item->getPrice(),
            'quantity'  => (int) $item->getQtyOrdered(),
        ];
    }
    // Queue for async server-side dispatch rather than blocking checkout
    $this->queueManager->push('ga4_purchase_queue', [
        'transaction_id' => $order->getIncrementId(),
        'value'          => (float) $order->getGrandTotal(),
        'currency'       => $order->getOrderCurrencyCode(),
        'items'          => $items,
        'store_view'     => $order->getStore()->getCode(),
    ]);
}
*/