If he has the power bricks for the devices with him then I expect their input requirements could be supplied without too much issue. By world war 2 the mains electricity standards we use today were already in use in some parts of the world.
Plus the input requirements of modern power bricks are very lineant. The things usually have a nominal voltage range of 100V-240V and are designed to accept a tolerance band either side of that. So anywhere from about 90V to about 264V AC would work. Frequency on the label is usually shown as 50-60Hz but again that is a nominal range and there will be wide tolerances either side of it. Many bricks will even run on DC though I would consider it risky to try that on an unknown one.
If he doesn't have the power bricks it would be harder and there would be a greater risk of an accident frying something.
