So far i found one person who can exchange them with you but is faction related so not always available.
Grey army is obviously slavic related.The guy has slavic name and weapon.
Old NPC, or from expedition? The only one I can think of with a very slavic name is Prevlic.
He means Kokoschka. As a result, you need to be a member of the Free Drones in order to have the option to trade in the Gray Army dollars for charons.