I realize this is on Amazon.ca but I’m sure you’ll find it on Amazon.com. This works well for us for SMALL appliances (like electric toothbrush). A hair dryer would fry this since it’s only rated for 70 watts.

LINK

Voltage Converter, Step-Up&Down Voltage Converter Transformer 70W 110V/120V to 220V/240V 55-60HZ

You would need the two prong adaptor as well to plug it into the French socket.