I'm not going to spend too much time debating a tankie, but I think most of these regimes kinda by definition are not socialist given how little power the workers had.

Using the USSR as an example, the workers had far more power and democratic participation in the economy. They couldn't have had much more, unfortunately, because democratic participation requires planning, and planning requires development. The USSR was underdeveloped, so it could not have been more democratized than it was.

When unions are suppressed and the military and the dictatorship are essentially the same thing, how could they be socialist?

They had a publicly owned and planned economy, drastically reduced wealth disparity, centralized production, and had universal free healthcare and education.

Socialism requires that workers own their workplaces, that they run them.

Incorrect. You are referring to cooperatives, which is not the same as Marxism. Engels actually wrote against such a system in Anti-Duhring, as cooperatives without central planning and ownership begets accumulation and competition, serving as a breeding ground for Capitalism. Cooperatives are not Marxist, because it transforms the proletarians into petite bourgeoisie.

This was not the case in the soviet union nor is it the case in china today, where businesses are either organized by the state (like in the soviet union) or mixed (CCP).

You're describing Marxism and saying it isn't Socialist, I am not sure what your point is. State planning is Marxist.

The state organizing businesses or whatever you want to call them would be fine if the people owned the state, but again these were/are dictatorships.

They were and are not dictatorships, from Soviet Democracy to whole-process people's democracy, there are democratic structures in place. It isn't liberal democracy, but it is democratic.

The people don't control anything at all in your so called marxist states, and so therefore they are not marxist.

Oh, but they did. You can read the linked sources.

Centralization is not something that I'm opposed to, but what does it matter how decentralized or centralized something is if it's not also democratically owned?

They were and are, though, this is a point you just assert over and over again without anything backing it up.

I would probably call myself a marxist if tankies hadn't so thoroughly stained the term.

I encourage you to read Marx. I understand that you likely won't agree with what I am saying in this comment, but if you want reading recommendations I can give suggestions. In particular, I think you should study Historical and Dialectical Materialism, a thorough understanding of each helps place AES countries and their successes and failures into context.