Isolated Power Supply Modules
Take a look at the SN6501 and, if it isn't what you need then you can use the keywords in its description to find an alternative.
It's used quite extensively for isolating bus power on such systems as RS485 repeaters: -

As for isolation, the transformer shown above will need to have the requisite insulation properties between primary and secondary. See this extract from the above data sheet: -

The data sheet also might provide you good circuit ideas like this: -