Cryptocurrencies are a drop in the ocean in terms of helping a country to overcome economic sanctions. You might seem curious but Russians aren't as sanctioned and limited as many think. Many countries buy products for Russia and deliver them, for example, Armenia buys 10000 Mercedes car, then Russia buys from Armenia and that's how Russia gets rid of sanctions. Also, as far as I know, many companies changed brand identity in Russia to bypass regulations and restrictions.
Sanctions are stupid to my mind, with or without cryptocurrencies, Russia can evade many of them. Btw cryptocurrency mining will be very cheap for Russia because electricity rates are very cheap and China is their neighbour.
I also hear that they go over it by using third nations instead. So Russia sells something to X nation, then X nation sells that to Germany, that way Germany still buys from Russia, the only difference is that X nation makes money in the middle instead. Makes things more expensive for Germany to buy, and makes things cheaper for Russia to sell, because that difference will go to X nation instead.
However, that still doesn't mean that sanctions work, it just doesn't work for either, not for Europe, not for Russia, both are still dealing with each other. When you combine all the ways sanctions are broken there isn't really all that much that still stays unused, it is trading and all nations are dealing with each other aside from maybe a few products.