Attachment Viewer is a new (as of the July, 2019, ArcGIS Online release) configurable app. It's intended to provide an easy way to browse feature layer attachments of all types - images, photos, documents, videos, and more. It can be used to view photos captured with Collector for ArcGIS, Survey123, QuickCapture, and other field and desktop apps.
Learn more by reading Browse feature layer attachments using Attachment Viewer in the ArcGIS blog. You can also view the Esri Campus Locations sample app.
One of the nice capabilities of the app is that you can navigate to any feature, and browse to any attachment, and can share the location and attachment via URL, shortlink, Facebook, and Twitter.