You can share actions and reusable workflows within your organization, without publishing them publicly, by allowing GitHub Actions workflows to access a private repository that contains the action or reusable workflow.
Any actions or reusable workflows stored in the private repository can be used in workflows defined in other private repositories owned by the same organization. Actions and reusable workflows stored in internal repositories cannot be used in public repositories and actions and reusable workflows stored in private repositories cannot be used in public or internal repositories.