I think it’s both, but most of the content that appears will appear under the microblog section, because that’s where most users posting content to gup.pe groups live
And as an FYI, when I looked at !adhd on my local lemmy instance, it has content already federated to it, so that’s a good sign!
And as a further FYI, !fediversenews, which is a friendica group (works the same way as a gup.pe group) had a huge amount of content already showing in lemmy when I looked, which suggests it’s federating well
The adhd group isn’t populated on my end (lemmy.ml) … which is actually helpful information because that probably means it’s a federation/cache thing and not a software problem … good sign indeed.
It most likely means that someone on my instance has already discovered and used this feature to subscribe to the two groups I mentioned, but no one on your instance is following them yet