In order to support disconnected Openshift usage, all operators need to support loading images from cached, internal, registries.

For OLM, I am not sure if there is a doc yet, but you can follow these instructions to load in the offline catalog. This process will get better for 4.3.

In your Operator, you should support the ability to pass in a registry hostname and path to an image, should someone want to import your required operand images, similar to the catalog experience. For example, this is a MariaDB CR:

apiVersion: charts.helm.k8s.io/v1alpha1
kind: Mariadb
metadata:
  name: example-mariadb
spec:
  image:
    debug: false
    pullPolicy: IfNotPresent
    registry: docker.io
    repository: bitnami/mariadb

Plumb that all the way through into your code where you construct your StatefulSet or Deployment. Another example is Prometheus, which allows you to pass in args for the images that it uses.