Opinions on `images`?

This would be a <picture srcset> but we do not know how widely this would be supported.

See also example 51 in the Spec.

{
  "@context": "https://www.w3.org/ns/activitystreams",
  "type": "Image",
  "name": "Cat Jumping on Wagon",
  "url": [
    {
      "type": "Link",
      "href": "http://example.org/image.jpeg",
      "mediaType": "image/jpeg",
      "width": 400
    },
    {
      "type": "Link",
      "href": "http://example.org/image.png",
      "mediaType": "image/jpeg",
      "width": 1920
    }
  ]
}