For those who don’t know, a.gup.pe is an independent service that brings group behaviour (somewhat like communities here) to mastodon. It’s kinda nice and quite a few use it on mastodon.
Interestingly, it seems you can subscribe to one of their groups from lemmy!?
I just tried !blackmastodon@a.gup.pe and it seems to have worked and showed up in the community search! Not sure if posts are actually federating though, which would make sense as many might not know about this.
This might be a nice example of the two platforms being pretty compatible with each other??
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