@JanKusanagi Oh, is that how it's supposed to work? It doesn't present that way anywhere, pump.io contacts are followed just like normal contacts, and I haven't seen anywhere to link up with a native pump.io account.
But I can see that friendi.ca offers no pump.io metadata at https://libranet.de/.well-known/webfinger?resource=acct:clacke@libranet.de so you seem to be right that it's not even trying to be a pump.io node.
I have been able to follow several pump.io accounts from within friendica, but I haven't received a single message from them, which would of course be impossible if they can't even find my inbox.