IMHO, the pure Russian or European Boar that is free roaming anywhere in the US is a modern myth.
Something to ponder though; the Spanish brought many domestic (Asian) strain hogs to Florida in the 1400s. They have been roaming around breeding wild here ever since. Thats wild enough for me. I've seen brown hogs, spotted hogs, white hogs and plenty of black ones in my 40 odd years of hunting and been charged at one time or another by every color.
I've carried a 9 inch scar on my right shin since I was 24 from a black, 80 lb, boar that slashed me with barely a one inch cutter. The memory of that pain is still vivid. "Feral" hogs are "wild" hogs and are potentially dangerous. If you want a "Russian" boar, go hunt them in Russia. You are not likely to find one on a affordable hunt in the U.S. unless he was recently imported to a high fence "preserve". My back door hunting grounds are dangerous enough for me.