On the topic of left unity, it should be a priority to gather with as many comrades as we can. Imperialism certainly won't be brought down by sectarian social media cliques, it will be brought down by the people in resistance. The task of organizing rests upon all of us. We can maintain internal criticism among leftists while maintaining our solidarity (unity, struggle, unity) without condemning each other.
If we can't uphold unity, then we fail the task of organization. The reactionaries win.