Hi, welcome to the conversation, you should probably read the things I already explained.

The liberal understanding of democracy (that you're operating on) is constraining the power of the state, while ignoring class conflict. The Marxist understanding is a state where the people have succeeded in class conflict to the point that they are able to wield the state against the bourgeoisie, while keeping them out of power. The fact that the communist party has secured power is not somehow a strike against Vietnam, from the Marxist view.

It's always funny to hear this scaremongering over "one party states." I live in the US, where I have a choice between one party that represents the interests of billionaires and another party that represents the interests of billionaires but also hates gay people. When I vote for a third party that's actually in line with my interests, everyone hates me for it. And you know what they say? "The primary is where you're supposed to choose who you like, but then you have to get behind them, to stop the Republicans!" Well, even single-party states still have primary processes, and in a case like Vietnam, you don't even have to worry about the threat of an entity like the Republican party coming to power, thanks to the structure of the government suppressing the political power of the right.

If a one-party state is so horrible, it implies that the Republican party (and similar parties in other countries) existing is somehow a good thing, somehow fulfilling a necessary condition for a country to be a "democracy." Even though it's controlled by a tiny fraction of society and uses every ounce of political power it has to subvert and oppose popular policies!

With that being said, you don't even have to be a member of the communist party of Vietnam to run and hold office in the country. You don't have to be a part of any party, you can run as an independent, and people do.

And yes, ditto for Cuba, I am "seriously" calling it a democracy.