I know some online shop owners and it's not hard at all. Some already reacted to other sanctions by blocking traffic from russia, as well as auto cancelling all orders with russian billing or shipping addresses. Sone also had to react to Iranian sanctions a while ago. And others block Chinese traffic, because their target audience isn't there, but there is constantly cyberattack probing originating from there.

Russia easily bypasses sanctions via its neighboring countries like Kazakhstan and Uzbekistan. They order to their warehouses there, then send to Russia.