It's never been "in practice". Without the dictatorship of the proletariat, you do not have Marxism.

Which is one of the problems with Marxism. Someone has to set the wheels in motion for a societal change of that sort, but once that person has that power, they don't give it up. Lenin didn't. Mao didn't. So you do end up with an authoritarian state which is not Marxist, and not even really communist. The USSR tried to make a show of workers sharing everything, but it wasn't ever really communism. China quickly realized that, and made their compromise with capitalism pretty early-on, which is why -one reason- their economy is generally better than the Russians' (even before the breakup of the USSR).

In both cases, the state owned the means of production (to varying extents), so it was a form of socialism. Compare and contrast to fascism where the state controls industry, but doesn't own it, and workers are paid in a more capitalistic fashion.

Harris is neither a Marxist, nor a communist, nor a fascist, nor an authoritarian. Her policies seem to be more pro-business than Biden's, in fact, but she still favors UHC and other left-leaning policies. And she favors democracy.