There is an extension API in OLM named PackageManifest that contains information about existing CatalogSources, which is essentially a repository of CSVs, CRDs, and packages that define an operator in the cluster. By querying that API, you can see the list of available operators.
There are two different types of CatalogSource in OLM: global and namespaced CatalogSource. The global CatalogSource contains operators that will be available for all namespaces while namespaced CatalogSource only contains operators that are only available for a specific namespace.
You can use these example commands via kubectl CLI (kubectl) to list available operators in a specific namespace. PackageManifest will return the union of global, which are available globally, and namespaced operators in namespace you’re requesting.
$ kubectl get packagemanifest -n <namespace>
The list of available operators will be displayed as an output of those above commands:
$ kubectl get packagemanifest
NAME CATALOG AGE
cassandra-operator Community Operators 26m
etcd Community Operators 26m
postgres-operator Community Operators 26m
prometheus Community Operators 26m
wildfly Community Operators 26m