For instance, this one (link to a post to !memes@reddthat.com): https://reddthat.com/post/20260613
Pasting it in your search bar should give you this kind of results:
You can then click on it to access the post from your instance (in this example, lemmy.zip: https://lemmy.zip/post/16918691)
Eternity and Thunder seem to most of the time, but it occasionally fails, even for non-obscure instances.
Good to know. And just good in general. lol. It was a fairly simple feature to implement, and I was hoping more UIs would adopt something like that.