Russians already had nvg tech, What they tried to copy was integration between the low and high spectrums so green nvg vision and thermal could be integrated into one device. Russia has been able to keep up for quite some time on both thermal and nvg, but has been using them as seperate devices, which means more gear to carry and more logistics, while america has made the same tech merged in some devices and made them smaller and lighter.
However with third world countries where night time fighting is often used in urban combat, gen 1 and gen 2 are all that is available, gen one russian nvg is widely available, but is pretty crappy, But russia has stockpiles of them because during the soviet union first gen nvg tech was a fraction of the cost, and with a giant military to arm they needed cost cutting somewhere. Second gen I have rarely seen available through russia as their military still widely uses it for general forces where more expensive nvg's are not needed. Gen 2 is available through the civilian market but gen 1 russian surplus can cost around 300 bucks a set, gen 2 russian surplus or civilian can cost around 1500-10k a set, not something your average ragtag insurgent can spring for.