My two cents on how to achieve left unity:
Anarchists: Stop using the word tankie. It pushes your fellow leftists away and pisses them off. Instead make specific criticisms of communist countries. ESPECIALLY stop calling MLs “red fash”. There is already enough misinformation going around about fascism.
Marxist-Leninists: Embrace critical support. Be willing to criticize and accept criticism of nations like China, the Soviet Union, and especially North Korea. Remember that being against US imperialism is not the only thing that makes a country good.
Marxism is not moralistic! Even considering particular policies as "good" or "bad" is misleading. The actual question is "is ______ giving power to the proletariat?"
The difference is that Bernie is the only socialist politician, where those states have long histories of virtue signalling their communism. Deng literally had the audacity to call himself communist despite removing Marx