Now I did not know this but the PAK40 was used in tiny numbers by the NVA.
But only up North, mostly for training and IIRC coastal defence. Actually, early on, they were the recipient of a shitload of ex-Wehrmacht kit, warehoused by the Soviets. Mauser K98s, MG-34s, the odd MP-40 etc. German small arms turned up with such frequency in captured NLF caches, that the US included them in intel and training briefs.