You can get some nifty fold-flat BS1363 doodads, though. I have a USB-C charger that collapses into something about the size of a stack of 6 credit cards. Something similar is currently available as the "Galvanox Flat USB-C Charger" on Irish Amazon.

See also: https://plugsocketmuseum.nl/GB-foldingPlug1.html

My international travel "brick" for laptop + phone is an Anker PowerPort Atom III Slim, which is flat multi-port charger with an IEC-320-C8 input. For the Continent, I plug in a "0cm cable" that's a Europlug nub. For US and UK/I, a NEMA cord with a compact BS1363 "shaver adapter" with a 1A fuse in it. Really wish I could get something flatter to be the adapter! Maybe I'll have to make one.

That is pretty nifty. I used an Anker A2669 for travel within the UK, a bit chunkier but also with folding pins.

I appreciate that they seem to put some effort into the design of their UK only products, instead of just shipping a US/Cn shaped charger with a BS1363 plug grafted on