Proper galvanic isolation is most of what protects you from mains. The YouTube channel Diode Gone Wild does a lot of charger teardowns explaining what makes the

Proper galvanic isolation is most of what protects you from mains. The YouTube channel Diode Gone Wild does a lot of charger teardowns explaining what makes them safe or dangerous. Unfortunately, we often rely on trusting secretive vendors with insulation specs, trusting assemblers with following instructions and not damaging hard to inspect wiring and insulation, and trusting brand and certification markings on the product since you can't open it without destroying it.