Okay, so here's the thing. The Soviet Union was not originally intended to be merely the Russian Empire draped in red bunting. It was a union of allied socialist states intended to be a prototype world government. That goal was forgotten very quickly, but it's kind of the whole raison d'etre of the union treaty.
You only get a Chinese Soviet Socialist Republic in a TL where the Soviet Union had already greatly expanded beyond the borders of the Russian Empire. So, a successful German Revolution and other eastern European states that ratify the union treaty, making the Soviet Union more like the EU with teeth.
Even in 1920, though, the idea of a soviet federation embracing , say, central Europe, was already being discounted by Stalin. To quote an old soc.history.what-if post of mine:
***
As Robert Service notes in his *Stalin: A Biography* (pp. 179-80) this
question was being debated in the summer of 1920--not only for Poland but
for Germany as well--by Lenin and Stalin:
"Stalin and Lenin also undertook preliminary planning for the kind of
Europe they expected to organise when socialist seizures of power took
place. Their grandiose visions take the breath away. Before the Second
Comintern Congress, Lenin urged the need for a general federation
including Germany, and he made clear that he wanted the economy of such a
federation to be 'administered from a single organ.' Stalin rejected this
as impractical:
'If you think you'd ever get Germany to enter a federation with the same
rights as Ukraine, you are mistaken. If you think that even Poland, which
has been constituted as a bourgeois state with all its attributes, would
enter the Union with the same rights as Ukraine you are mistaken.'
"Lenin was angry. The implications of Stalin's comment was that
considerations of national pride would impel Russia and Germany to remain
separate states for the foreseeable future. Lenin sent him a 'threatening
letter' which charged him with chauvinism. It was Lenin's objective to
set up a Union of Soviet Republics of Europe and Asia. His vision of
'European socialist revolution' was unchanged since 1917. But Stalin held
his ground. The Politburo had to acknowledge the realities of nationhood
if the spread of socialism in Europe was to be a success.
"These discussions were hypothetical since the Red Army had not yet
reached Poland, far less set up a revolutionary government in Warsaw..."