WooCommerce
WooCommerce offers hooks that make proper dataLayer pushes straightforward. AtriTap generates the plan and the dataLayer spec; your developer wires add_to_cart, begin_checkout, and purchase through woocommerce_add_to_cart, woocommerce_checkout_order_processed, and woocommerce_thankyou hooks.
The lightest option: a plugin that only inserts the GTM container snippet. Heavier 'GA4 for WooCommerce' plugins often duplicate tags; AtriTap's plan replaces them.
Subscription renewals are a different event than one-off purchases. The baseline output handles initial purchase; renewal tracking is a small extension handled in the dev brief.