Contributions from russians make up a sizeable portion of Linux and GNU tooling. A myriad of foundational software, from nginx to strace, were created and are currently maintained by russian citizens.

While there has been a lot of brain drain (hello), russia is still a country of 140 million people and the remains of great soviet theoretical education. In such conditions there will be both a bunch computer science geniuses and a small army of half-competent coders which would allow you to roll your own OS, let alone a distro, if the efforts were organized enough.