IT department (my IT literate daughters) contacted re USB stick. I like the sound of that, as long as the user interface is OK (searching for artists, tracks etc). Anything will be better than what I have now!
Thats good.
The other option that should work with Amazon music through Car Play, rather than through Hyundai’s version is a USB C to Lightning cable, as shown from Apple, but cheaper on Amazon.
https://www.apple.com/uk/shop/product/MUQ93ZM/A/usb-c-to-lightning-cable-1m