I always took "build in public" as a prompt to share what you're working on, and interesting tidbits about your work. In my case, it's mostly because I don't get to talk shop otherwise. My posts are a mix of German bureaucracy updates, web development "TIL"s and new handmade illustrations.

I find that talking about income fosters the wrong kind of discussions with the wrong kind of people. These discussions tend to be extractive rather than conversational.