I think Sanders or Warren would have been more radical than Biden, but I doubt any of them would have been effective in carrying out even a moderate liberal mandate, let alone a progressive or a socialist one. The next Democratic president will be too busy fixing all the damage Trump has done (just as Obama had to fix Bush Jr’s), and any Democratic president has to fight the Republicans every step of the way. Republicans are far superior in all aspects of politics (lying is the main job requirement), because they’re more flagrant about their psychopathy, and they don’t credit any Democrat with even minimal legitimacy. Republicans see only themselves as authentically American, let alone as worthy of leading the country.
There is a an ideology of liberalism that Democrats could call on, as Yuval Harari points out in Homo Deus, but Democrats have lost touch with their ideals. In part, this is a problem with secularism. Progressive values are atheistic or humanistic and don’t make for compelling myths, compared to the traditional religious values which give cover to Republican social Darwinism and to their worship of free markets and plutocrats. Democrats have had to sell out their ideals, to compromise with Republicans in holding the political center.
The TV show Cosmos exhibits the values of secular humanism, and Democrats should at least be trumpeting those more universal aspirations (coming together in the use of science and technology for the good of all humankind, as in optimistic science fiction). But that globalism is out of fashion now. Nationalism, xenophobia, and right-wing populism (bigotry) are on the rise. In short, either way you look at it, I don’t see much progress coming from American politics for a long while.