I am trying to migrate ingress-controller based ingress which uses internal load balancer with managed instance group as backend to istio based load balancer which uses Service object and will spawn an ILB with unmanaged instance group as backend, I want an L4 load balancer. However, that setup is apparently not allowed in GKE as worker nodes can only belong to at most 1 load-balanced instance group.
Now, I am trying to find a way to work around that restriction, i.e. spawning istio gateway using an internal passthrough load balancer (L4) and using zonal NEGs as backend. Is it possible to do that?