Can I create a collaboration from arcsde reference feature service to a local hosted read only copy?

Hi Jared, Yes you will be able to share the feature layer (from your Enterprise GDB) as a copy to Portal 2, you just need to ensure the feature layer is sync-enabled before publishing from Pro to Portal. See the documentation below: Share feature layers from an enterprise geodatabase—Portal for ArcGIS (10.6) | ArcGIS Enterprise Hope…