This style of cable used to be everywhere in the US, but now I can't find them anywhere, except for wholesale sites that require a large minimum order. Ebay and Amazon are useless as well.
As far as I know, those were mainly used in shavers with one of those coiled cords. Since virtually all shavers are cordless now, perhaps the cables are becoming rare too? What do you need it for? My radios mainly use C7.
C7 was mostly Euro. But in the US most boomboxes used C1, or a rectangular one that doesn't even appear on the IEC charts anymore.
There were some cheap rechargeable razors, lint removers etc, in which the charger was built into the unit which used those leads. It might be easier to look for one of those than a lead on its own. Edit. No problem finding the curly cables here https://www.ebay.co.uk/itm/391685974702 I even found this more normal "vintage" one https://www.ebay.co.uk/itm/377052042396
Unfortunately most of those seem to use a C5 or C7 to fit into the brick. Yeah I thought about those, but they're quite unattractive. Plus the longer a cable is, the more internal resistance it offers.