To use API Gateway, you must install Istio on your cluster. This is required because API Gateway creates the custom resources Gateway and VirtualService, which are provided by Istio. The recommended method for installing Istio is by using Kyma Istio Operator.
In SAP BTP, Kyma runtime, API Gateway uses DNSEntry and Certificate custom resources provided by Gardener. Because SAP BTP, Kyma runtime uses Gardener as the running environment, managed offering users are not required to install any dependencies manually.