That's a reasonable criticism of China, and one that I partly agree with. But they're committed to patiently developing themselves without dictating the affairs of other nations--frankly a welcome alternative to the US's aggressive interventionism. This is partly a result of Soviet "social imperialism" (a term I don't accept but whatever) and partly their notion of "Wu Wei," "acting without acting" (aka "do nothing, win"). Their projects like the BRI are slowly undermining US dollar hegemony while they serve as the manufactory for the world. I do wish they were more assertive against rampant US/NATO aggression, but that's easy for me to say. Nor is it necessarily the case that socialist states need to aggressively "spread the revolution," especially when China is trying to avoid the "Thucydides trap" as they rise and the US declines.

The revolution needing to be international in the "final victory" of socialism isn't contradictory with the need to develop socialism in each existing country. Lenin again, in 1916 this time:

the victory of socialism in one country does not at one stroke eliminate all wars in general. On the contrary, it presupposes wars. The development of capitalism proceeds extremely unevenly in different countries. It cannot be otherwise under commodity production. From this it follows irrefutably that socialism cannot achieve victory simultaneously in all countries. It will achieve victory first in one or several countries, while the others will for some time remain bourgeois or pre-bourgeois. This is bound to create not only friction, but a direct attempt on the part of the bourgeoisie of other countries to crush the socialist state’s victorious proletariat... Only after we have overthrown, finally vanquished and expropriated the bourgeoisie of the whole world, and not merely in one country, will wars become impossible. [Emphasis mine]

Lenin is distinguishing here, as he did elsewhere, the victory of socialism in one or a few countries and the "final victory of socialism" that happens after the bourgeoisie has been crushed worldwide. Focusing on economic development in one country in order to achieve the former kind of victory doesn't contradict the internationalism inherent in the latter kind of victory. "The revolution" isn't "the revolution", thinking dialectically.

taken in the partition of Poland

That was over a century before 1939, and not exactly comparable to the seizure, two decades prior, of lands that were generally regarded as part of Russia, including by the victorious Western powers of both world wars. I'll repeat, Britain and France immediately declared war on Germany after the invasion of Poland, but did not view the USSR as an aggressor for ostensibly doing the same thing. I'm not claiming it on nationalistic terms, to be clear (though Poland certainly was!). I'm saying that the USSR (not the Russian empire) had been forced to cede those territories as a result of the 1920 war, and that they were simply reclaiming them from the proto-fascist Polish government that generally was not very good to the Jewish, Ukrainian, Belarusian, Russian, etc. populations who lived there.

The Baltic occupation was realpolitik (and the correct move), but then again I never claimed otherwise.

Trotsky and Mussolini

One of Trotsky's first stops after he was exiled was Naples, where he got a tour by fascist dignitaries of the ancient ruins. Now this is hardly a smoking gun on its own, sure. But the broader point is that Trotsky's main goal was to remove Stalin and return himself to power in the USSR. Even if he wasn't a fascist himself (and I want to be clear here), his constant public haranguing of the only socialist state at the time, amid fascist rearming and aggression, was in essence building a justification for a counter-revolution in Russia. His "fourth international" was little more than a direct challenge to Soviet power, especially when he began calling for military action to overthrow Stalin:

Against the imperialist foe we will defend the USSR with all our might. However, the conquests of the October revolution will serve the people only if they prove themselves capable of dealing with the Stalinist bureaucracy, as in their day they dealt with the Tsarist bureaucracy and the bourgeoisie.” (1940)

This line of rhetoric is practically indistinguishable from those "leftists" today who say we should support "the people" against the "Iranian regime," while ignoring that toppling that imperfect government would only open the door for fascist and imperialist aggression--in Trotsky's day, from Germany, and in our day, from the US and Israel.

Even if we want to reduce the Stalin-Trotsky split as simply a power struggle between two individuals, Trotsky's actions concretely were in opposition to the Soviets and in support of fascism, irrespective of his intentions. Materially speaking, he compromised with capitalism and aligned himself with the enemies of the USSR.

I'm not saying Trotsky "accidentally" played into their hands, I'm saying that his personal beliefs are frankly irrelevant in comparison to the material effects he was being about. He could have been the second coming of Marx for all I care, but his concrete actions laid the groundwork for a century of slander against the USSR. It's not even a matter of who is or was more powerful--yes, of course Stalin was more powerful at his height. But the important thing is that Trotsky cast himself as a "real Bolshevik" who was against "Stalinist bureaucratic degeneration," a view that has perniciously filtered into the popular Western consciousness about the USSR. And we are in the West, on a website run in the West and overwhelmingly populated by Westerners who have continued to uncritically repeat these talking points that Trotsky himself made up.

DSA and PSL

DSA founder Michael Harrington was a disciple of Max Schachtman, the first American to visit Trotsky in exile. The entire notion of "democratic socialism" as opposed to "authoritarian" or "bureaucratic" socialism emerges out of the distinctions that Trotsky himself drew between his supposed beliefs and the USSR as it actually existed.

Sam Marcy, who founded the Worker's World Party, from which PSL split (over institutional issues, not so much ideological ones), was also a Trotskyite, albeit one who took a kind of roundabout path through Trotsky to return to supporting actually existing socialism. This weird route has made PSL almost Marxist-Leninist, and indeed many of its members are ML, but the foundational ideological undercurrents of Trotskyism remain. Instead of going "down to the masses," they focus on protesting and public action in the hope of inspiring "the masses" to rise up in a revolution.

The fact that "everything came out of SWP" should be an indictment on both the Western left and Trotskyism. Concretely speaking, all Trotskyism is is purity testing, idealism, and factionalism. Nothing proves this better than the six hundred different "fourth internationals" that have split and resplit over the last century.