The actions and reusable workflows from private repositories can now be shared with other private repositories within the same organization, user account, or enterprise.
See managing the repository settings and managing the enterprise repository settings to allow access to workflows in other repositories.
We have also added the API support to configure Actions share policy. Refer to API support or API support for Enterprise for more details.
Learn more about Sharing actions and workflows from your private repository, Sharing actions and workflows with your organization, and Sharing Actions and workflows with your enterprise.