operatorgroup.yaml

apiVersion: operators.coreos.com/v1
kind: OperatorGroup
metadata:
    name: operatorgroup
    namespace: <TODO-EXISTING_NAMESPACE>
spec:
    targetNamespaces:
    - <TODO-EXISTING_NAMESPACE>

operatorsource.yaml

apiVersion: operators.coreos.com/v1
kind: OperatorSource
metadata:
  name: crw-operatorsource
  namespace: openshift-marketplace
spec:
  type: appregistry
  endpoint: https://quay.io/cnr
  registryNamespace: crw
  displayName: "Custom Operators"
  publisher: "Red Hat"

pseudoscript

if operatorsource is not present on cluster
  oc apply -f operatorsource.yaml
fi

oc new-project myNamespace

change <TODO-EXISTING_NAMESPACE> to `myNamespace` in all the files

oc apply -f operatorgroup.yaml
oc apply -f subscription.yaml

# Now the situation in the cluster is the same, as you would "install" operator through operatorhub

oc apply -f checluster.yaml

subscription.yaml

apiVersion: operators.coreos.com/v1alpha1
kind: Subscription
metadata:
  name: codeready-workspaces
  namespace: <TODO-EXISTING_NAMESPACE>
spec:
  channel: latest
  installPlanApproval: Automatic
  name: codeready-workspaces
  source: crw-operatorsource
  sourceNamespace: openshift-marketplace
  startingCSV: crwoperator.v2.2.0

Note to self: checluster.yaml = a CR yaml like https://github.com/redhat-developer/codeready-workspaces-operator/blob/master/deploy/crds/org_v1_che_cr.yaml or some variation