Yes, why not, you can buy anything - DAI, USDT, BTC, SOL, etc but if you don't want to pay ANY fees then the only coin you can buy with absolutely ZERO fees in US is USDC stablecoin on Coinbase. If you want to buy DAI - Coinbase will charge you 3% commission.
Not exactly true. Most largest international crypto exchanges still have RUB and both biggest Russian banks that are sanctioned (Sber and TInkoff) as official methods for P2P deposits and withdrawals. And I don't think they ever completely close the door for RUB to be withdrawn. Especially Bybit (UAE) and Huobi (China). You can actually still withdraw RUB on Binance too, no problem (Tinkoff is now Reiffeissen there and Sber is Rosbank :).
Pretty much like Dobryi Cola or Lubimaya Cola in Russia. Officially Coca Cola and Pepsi left but in fact they just renamed their products and keep making money like before.