This is Market Socialism, not Marxism. Marxism is what is depicted in the above graphic.

The graphic with the big caption "SOCIALISM". But fair point on me not addressing the specific implementation suggested with the presence of the Marx and Lenin characters.

If your aim is to get into the weeds about what is considered Capital, edge cases can be decided by committees.

Well yea, the devil is in the detail so it can't just be waved away. The "commodity production process" still implies physical goods made from physical resources and that it's the production facilities and resources that should be seized. (Side note: this assumes all the underlying resources are present within the area controlled by the proletariat.) Not seen any ideas proposed beyond that, but perhaps I'm not hanging around in the right places... Hopefully the committees will have people available that can figure it out after the fact?

Requirements can be decided by the people. These committees are held accountable via election, and a recall election can be held at any time. There are multiple rungs of planning, from society wide to regional to facility levels, with committees for each. They can serve planning and execution, as workers participate.

Yea, you've clearly never worked in a "design by committee" or "management by consensus" situation. Nothing ever gets done, and when some decision is finally made on anything it tends to be the shittiest common denominator option that thinly and evenly spreads the collective responsibility. Not the best option, but the one that everyone can kind of agree on and thus be collectively accountable for. The exception might be when a very small number of people that are agreed on an end goal and share the same vision for reaching it work together. But I assure you, that does not scale - even if people are in full agreement on the end goal.

Why would producing more tractors in collective 631 benefit that collective if the goal is to satisfy the whole from the whole?

Because human beings.

Managers are not a class, they are an extension of the workers.

Fair point. I guess I was a bit caught in the popular narrative where managers are the enemy of the workers.

Yes, across numerous studies worker participation in steering companies has resulted in higher satisfaction and stability.

Of course, and I'm a fan. I'm not disputing that places where extensive consultation happens with the people responsible for delivering are nice places to work at. But that consultation process is usually very closely managed and the ideas to take forward are cherry picked to give enough "they listen to me" feel good vibes, while also not interfering too much with the business' priorities. Really taking the inputs of large employee groups seriously on the things that matter cannot happen outside of an adversarial setting, because the interests of the worker and those who benefit most from their labour are fundamentally in conflict. The point I'm rambling towards is that I doubt there are studies that looked at situations where employee inputs in decision making (beyond window dressing) was sustained over very long periods of time at a scale relevant to what you envision. (There are exceptions, but only in small groups of highly-aligned people in a horizontal structure that are deeply vested in the success of the venture.)

You’re arguing against a chimera of random mish-mashed ideas from several different strains of Socialism that argue for different forms as though they are one and the same.

I guess you're right on that, yes. The thing is that I've been thinking about details like these (and many more) for at least 25 years (beyond "edgy teenager" or "social media fad" or "my parents are fascists" stages), since I would prefer that the fruits of my labour (to at least some degree) benefit other people rather than feed a system that heavily incentivises the shittiest parts of human beings and is also inherently cruel. Over the years I've also read pretty widely on this topic - from the purist theoretical ideologies to the practical compromises to the counterpoints to the criticisms. (Hell, I even lived in what was basically a workers' collective for almost a year, but it only worked because it was a small community of ~100 people with close social and familial ties.) So in my mind the lines between specific flavours of socialism are pretty blurry these days, while the common fundamental challenges keep standing out.

What truly frustrates me is the constant arguments about which is the best flavour, while ignoring how to actually realistically practically progress towards something better. Spending the day fighting about which flavour of ice cream to buy instead of figuring out how to get to the ice cream shop on the other side of the city in the first place.

That, and I am yet to see something proposed that doesn't completely ignore predictable human reactions or result in some degree of authoritarianism. (Nordic-flavour (kind of but not really) Market Socialism is perhaps the closest to something that might work, but it also heavily relies on a fairly homogenous society with a culture that sees value in the interests of that society over total individualism.)

You're not liberating literal serfs that never knew personal agency from a literal monarch. You're trying to get people that are exploited by a system while also benefitting from it to willingly abandon that system for something that might be better (if it worked) or might not be - the plans for the "something" are fuzzy at best so who knows. The details matter, and interrogating the details is not reactionary behaviour.