The floating power plants from Rosatom are like 70 megawatt, a pittance vs the blackouts Texas saw. The root problem in Texas was insufficient winterization of the grid, caused by the incentives of their energy market approach. This would have still been the case even if Russia had 100 reactors floating off the Texas coast ready to hook up.

There's significant latency in oil supply chains. Weeks if not months. Keeping a refinery online does not somehow keep a power plant online or the lights on in the cities in the proximate sense. Oil refineries are irrelevant to what happened.