Lemmy uses the packages olowe.co/lemmy (source), which provides a io/fs filesystem interface to a Lemmy instance, and 9fans.net/go/acme to interact with acme. What you get is an Acme Mail inspired program for Lemmy. As you can see, it's a work in progress!

But it's been fun so far. Sorry that this isn't running on Plan 9 (running on OpenBSD). I'm on the road at the moment and don't have a way to connect to a server right now!