Issue about hosting xml/html files to add new widget
One answer
Anything you want to link to from DNG has to be reachable from that DNG server. So you need to have access to a publicly reachable application/web server to deploy the files to publish.
Localhost is never reachable from anywhere than the local computer. Some cloud solutions provide tools to connect to on premises hosts e.g. the IBM cloud has the capability to connect using the secure gateway client.