Where does ConfigMap data gets stored?
Yes etcd is used for storing ConfigMaps and other resources you deploy to the cluster. See https://matthewpalmer.net/kubernetes-app-developer/articles/how-does-kubernetes-use-etcd.html and note https://github.com/kubernetes/kubernetes/issues/19781#issuecomment-172553264
You view the content of the configmap with 'kubectl get cm -oyaml' i.e. through the k8s API directly as illustrated in https://kubernetes.io/docs/tasks/configure-pod-container/configure-pod-configmap/ You don't need to look inside etcd to see the content of a configmap.