Because of how Google has decided to make life of engineers painful; I was forced to migrate using GKE-Gateway API to use wildcard cert since the ingress object don’t support it(supported by all other cloud providers).
Now once I finished setting gateway-api; I was able to see below gatewayclasses in my cluster
gke-l7-global-external-managed True 67m
gke-l7-gxlb True 67m
gke-l7-regional-external-managed True 67m
gke-l7-rilb True 67m
gke-passthrough-lb-external-managed True 72m
gke-passthrough-lb-internal-managed True 72m
gke-persistent-regional-external-managed networking.gke.io/persistent-ip-controller True 72m
gke-persistent-regional-internal-managed networking.gke.io/persistent-ip-controller True 72m
As any sane engineer would assume; if I need a passthrough L4 NLB in GCP then I would use gke-passthrough-lb-external-managed but once I use it; it throws the error that it has not been implemented