You definitely need to distinguish “electrical” devices from “electronic” devices but a safer approach is to read the plug.

• A power supply (ex. Phone charger) will be stamped with a voltage range and power draw, which probably includes everywhere but you can match it against the electrical service where you are. You may need a plug adapter but a simple mechanical adapter is sufficient.
• an electrical appliance (ex. Hair dryer) plug is probably not stamped with electrical requirements so the safe approach is to only use it in the intended country