You might want to make this meta community more obvious.
People new to federation are wandering elsewhere. If the logged-in screen is anything like what I see as a guest, I'm not surprised. I found this through my own instance's search feature.
That's a frontend question I'm too much of a backend gremlin to competently answer, haha!
With that warning, yeah, a distinguished meta/"help with PieFed* topic could be good. On LemmyNet there's a "local" page, which is the default, so people are nudged towards looking around on their own instance first. However, I get the feeling you're trying to expose the most active communities right off the bat as part of UX.