Right now, we are only able to view an instance's specific community, but I'd love to be able to view what's popular in that instance, especially that I do not know what communities that instance has.

EDIT And this is where it gets confusing...

If you want to view another instance from your home instance you need to do https://lemmy.world/c/thecommunityyouwanttoview@lemmy.ml

But there is no https://lemmy.world/c/lemmy.ml <-- this will return a 4040

Ideally there would be a https://lemmy.world/c/all@lemmy.ml or a https://lemmy.world/c/popular@lemmy.ml