Let me remind you that Russians, according to their own law, can only use foreign cryptocurrency exchanges to buy and sell cryptocurrency for fiat money. No such exchanges can legally exist in Russia, but the use of exchanges in other countries is explicitly OK.

In other words, the 100% legal (from the Russian standpoint) way to circumvent the sanctions, for example, when somebody in the USA needs to transfer money to Russia, would look like this. That US citizen buys bitcoin for US dollars on their preferred exchange (possibly in the USA) and sends the needed amount of cryptocurrency to a wallet belonging to the Russian citizen. Then that Russian citizen uses some cryptocurrency exchange e.g. in Singapore (or in any other country that didn't impose any sanctions) and gets Singapore dollars in exchange for the bitcoins. The Singapore dollars get sent to his bank account in Russia (OK, for companies it would mean some paperwork, basically a confirmation of the origin of the finds, but that's easily doable). Then he converts Singapore dollars to Russian rubles, which is a currency exchange operation internal to that Russian bank.

This also works in the opposite way.

Of course if every country imposes sanctions, then this scheme will stop working, because there will be no way to sell the bitcoins.