Noah Smith & Brad DeLong's Weekly Podcast, with Special Guest Geoffrey Kabaservice
I would say that democracy will be destroyed by state level nullification, but also by gerrymandering, Republican sabotage at the federal level, and outright fraud/violence in the 2024 election.
The John Lewis VRA will not stop any of that, but the progressives I read (e.g., LGM) don't think it will. It will address other problems, and those other problems are worth solving. But it's only the centrists who are refusing to take the steps necessary to solve the above problems.
As for whether liberals/progressives are bad at making alliances with moderate conservatives, saying that violates Murc's Law (only Democrats have agency). One might as well say that "moderate conservatives" are bad at making alliances with liberals/progressives; if the "moderate conservatives" really cared about democracy they would align with the liberals/progressives to support the structural changes we need.