Soviet Russia at that time was a global superpower that had developed nuclear weapons and was winning the space race. It only exported heavily to other communist states, but it definitely could do advanced tech and manufacturing.
Modern PRC and USSR aren't exact analogues, but the approach of their governments is clearly similar in this case.
Soviets winning space race during microchip era? I think you have mildly mixed up decades. Soviets were leaders till US put people on the moon, that was so far beyond what soviets were capable of this race stopped, and they just focused on ICBMs.
Soviet tech was sturdy and more primitive (thus more sturdy), much cheaper and they were willing to deliver it to anybody.
Modern PRC and USSR aren't exact analogues, but the approach of their governments is clearly similar in this case.