As a separate thread to this, I was thinking that someone must have already come up with a solution for this kind of thing.
My first choice would be a tweet-to-image generator, as this would be the easiest to display and would work across devices, no Javascript required.
There are a few sites like that out there, but they don't look for mass consumption. I didn't find any open source projects either, maybe that's something to look into doing.
I did however find
https://iframely.com which supports a huge number of sites to embed things, taking the URL and giving back the necessary HTML. And you can run your own hosted version too.
I might play around with this instead, if I can get it working then I don't have to worry about any Javascript stuff, and I'd get embeds for pretty much any site I could imagine at the same time.