Wide input range switching regulators exist but a 1:4 ratio is typical. Some support an even wider input range but finding a suitable one would be a problem.
The usual problem is preventing or handling the transition between discontinuous and continuous conduction modes as the input voltage and output load current vary over their entire range because frequency compensation requirement are variable in discontinuous mode where the duty cycle varies. This can mean using a much larger inductance to prevent discontinuous mode operation, which compromises performance, or using a topology like constant off-time which does not care.
For safety reasons, it might be acceptable or desirable to use a power transformer for input isolation *before* the switching regulator despite the extra weight and cost. Some old test equipment did this like the Tektronix 2225 series of oscilloscopes even though off-line switching regulators were available at the time.