what I find really distressing is that it’s not just Bernie; no mainstream person or organization with national reach is giving concrete advice and/or instructions on how to depose the oligarchy
What instructions are you looking for, exactly? Like, what are the instructions that 'should' be handed out at this point?
There's no simple, easy, or quick solution to this, and since the election, things have gotten considerably worse on the 'possible solutions' front. Calls to organize and seek alternatives to oligarch-controlled resources are the groundwork which orgs constantly call for but no one fucking heeds. So what're the instructions that will provide the solution that those calls haven't?