short code embeded images as featured image/thumb?

I have a travel blog mostly with photos embedded via a flickr short code

eg:
[flickr]photo:1234567[/flickr]
[flickr]set:1234567[/flickr]

And these are the only images in my posts. Because these are externally hosted and called by short code, they don’t get picked up when the post is searched for an image. Meaning no featured image, thumbnail, or open graph image for facebook to use as a thumbnail.

I know there are plugins to start manually creating a featured image, but I would like it to work for all existing posts, so one of the flickr images is used.

Is that possible?

Thanks