Would love to see the option to activate and maintain an Open Data Site via ArcGIS Portal. I believe currently it is limited to ArcGIS Online.
ESRI have brought in 'Sites' as of Portal 10.6.1. Sites is a view into your Portal that allows visitors to see a simplified view of your available data. And make a decision as to how this may be used (download, link to, make a web map, etc). The site can be configured to show your data at the most basic level, but Sites actually has so much more. See: Set up Sites in Enterprise Portal—Portal for ArcGIS (10.6) | ArcGIS Enterprise for how to set up a 'Portal Site'.
And the UC Video:
Retrieving data ...