Marx differentiates between workers directly managing production and a state acting as their proxy. Material improvements alone don't prove proletarian control

Socialism is not the electrification of Russia

as state capitalism can achieve similar outcomes while concentrating power in a minority.

Yeah, clearly, but you haven't proven it at all. The revolutionary conditions of the PRC have made it so that regular working people can engage with their government in ways impossible in the liberal world, I know from my own experience of being there and from studies like this one from famously CCP Elite backed Harvard which shows that the great masses of people are satisfied in their governance and feel engaged.

You can imply and say all day without evidence that the world's largest socialist country is purely in the hands of a ruling elite which comprises it's own economic class separate from the working class people it represents, but it doesn't make it true.