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.
I used to judge anarchists pretty harshly until I read some David Graeber and thought about how there isn't a country in the world that is truly accepting of migrant populations despite how incredibly beneficial they would be.
Climate refugees need a place to go, and I don't care if nations fall to accommodate them. Sea Peoples 2.0 have my uncritical support.