If you want a 'communist corporation', just give every employee shares. You don't need unions or whatever else. You could start a company right now that does that. Some big UK firms do a performance sharing scheme with everybody in the company, even cashiers. Granted it's not much money in real terms, but it's proof how flexible the corporate legal structure can be.
Co-operatives in this form aren’t communist. They compete for members, vendors and customers. They don’t have a monopoly on violence. They can be held accountable by the rule of law.
None of the above apply to communist governments. They have a monopoly on violence and the factors of production. That precludes an independent check on state power which, in turn, precludes the rule of law.