There are no embargoes on currency futures in the US. So far as I know there aren’t any embargoes on delivering rubles as part of a futures cash settlement either. Getting those rubles may get difficult. But currency futures are dollar cash settled…
My understanding is that futures are simply a contract between two parties. Ruble futures don't necessarily have to interact with Russia or any Russian individual.
There is no embargo. At the moment, US has imposed sanctions directly on Putin and other top Russian leaders, and a small number of Russian banks have been cut off from Swift. You are free to buy and sell Russian currency and stock if you want.
