Honestly, I at this point wonder if progressives would be better off running as Republicans. Trump has largely, at least on messaging, distanced himself from a lot of traditional Republican economics. His base doesn't really care much about traditional Republican policies like tax cuts or even deregulation. It's mostly just driven by grievance and raw rage against vague elites. Mostly that is directed against cultural elites, but that same movement could be directed against wealth inequality. And the Republican Party has proven itself much more receptive to new ideas than the Democratic Party has. The Republican Party can be taken over by charismatic figures, while wealthy donors and special interest groups largely control the DNC. This isn't likely to change any time soon. The existing Democratic leadership has more to gain by losing as a centrist than seeing a progressive win and force through change in the DNC.
I say progressives should try running as Republicans. Call yourself a "radical Republican," hearkening back the historical radical Republicans in the post-Civil War era. Say you were going to stick it to the wealthy, give the little guy a shot, and not do any DEI. Hell, repeatedly hammer the nepotism and social advantages the wealthy have as "wealth DEI." Rail endlessly against big business and elites. Vow to not appoint anyone who went to an Ivy League school to any position in your administration. Promise not to even talk to a single Wall Street Banker.
Obama proved himself a centrist, but he ran as a progressive. That's the crucial difference.