But really, going point by point is probably worthless

I agree. Each point could be an entire conversation in and of themselves. I am not trying to dismiss your concerns or the points you raise.

I guess what I'm most curious about is, concretely, what actually separates China from a capitalist system?

The class that's in power. Is the US Socialist because it has a state-run Post Office? No. The PRC is led by the CPC, which has a bottom-up and top-down organizational structure via the mass line. It has a market economy that it carefully manages, prunes, and allows to develop to the point of "harvesting," where it increases ownership.

Surely it's not just proportion of SOEs, or fucking Bismark was a socialist.

Correct, it would be anti-dialectical to purely look at snapshots of ownership and not trajectories and class dynamics.

The dictatorship of the proletariat" is going to be your answer, but I ask, "What separates China's 'DotP' from a liberal democracy?" Surely, it's not just their anti-corruption measures or then Deng really did destroy socialism and I guess Xi re-established it.

The practice of Whole Process People's Democracy is a large factor, but it's ultimately the sum of its parts. The CPC is a DotP, what separates it is who is in power, the bourgeoisie or the proletariat. We see the effects of this in privitization vs nationalization, large infrastructure projects or private contracts, an improvement in real wages and democracy for workers or restrictions.

So far, it appears that, especially in the last decade or so, these trends have been rapidly moving in the favor and direction of the Working Class, not the Bourgeoisie.

I don't know, it just looks to me like a state where the power is held by public businesses rather than private ones in order to keep its sovereignty. To be clear, I'd like to see it otherwise, I get no satisfaction from what I say and it was nice cheering for the emerging dominant power thinking that it was not merely historically progressive but actually represented major progress in world socialism, but ultimately I realized that it was mainly what I wanted to believe and soon came to see Deng as being just a massively more competent Khrushchev, who had the refinement in his approach to praise Mao while in practice being everything that Mao had warned China he was for many years.

China is an incredibly complex system, and I won't say your concerns aren't valid. I recommend reading The Long Game and its Contradictions and China Has Billionaires.