Random post, on the bus I saw one of those wall-mounted USB chargers with the plastic cover already removed (I did not remove it). This is what the PCB inside of it looks like.

Looks like there are two DC-DC converters, pretty simple. The board also appears to be conformal coated.

EDIT: Looks like this is just a COTS charging module. Searching "USB3.25", which is present on the sticker on the USB-A port, leads to this product page. The datasheet claims it is “equipped with a protection against overvoltages, polarity reversals and short-circuits(intentional vandalism).”.