Not that it's essential as Facebook has been rather good so far at inferring the values of the og tags for Gromit's well-laid pages, but would it be possible to add these og tags explicitly in a future update of Gromit? The mains ones being og:url, og:title, og:image, og:description
Again, it's not essential, but it helps a tiny bit towards social-friendly link sharing
None of my skins includes any social media coding, and I don't foresee that changing.
In this case, you couldn't even code-hack your way into it. When the skin is assembling the <head> section of the page, where those tags would go, it has no idea whether there will be any folder thumbnails, to say nothing of being able to determine what the image file names will be. That would require some pre-processing before the page is even created.
Hope is a good thing, I suppose, even when it's completely forlorn.
Long ago, having watched the endless torture of dhina and laza, I vowed that I would never touch two things - shopping carts and social media. They're the black holes of support.
ETA: I've come to detest Facebook with a blind passion. They crank out the worst software I have ever seen, and that's really saying something - I've been in the IT world since 1974. Their ability to store and quickly access billions of images and videos is a technological marvel, but their UI is a toxic waste site. And they change their API's on a weekly basis, no matter how much havoc it causes.
For me, it's the only way to keep track of what the "young ones" are up to - nephews, their wives, and the little ones (four of them, ages 5 through 8). If not for that, I'd delete my account and happily never see their godawful site again.
Facebook and Google are the perfect examples why the humanity is not mature enough for AI. As long as the profit is the primary goal the AI will outsmart us people/developers unprecedented ways to make money for a chosen few. Facebook made broken their API on purpose to deter people from hanging around on other sites and still enjoy being part of the fb community.