FWIW, my current Kindle is pickier about charging sources than any USB-C device I've ever owned. It absolutely refuses to charge via my alarm clock's USB port,

FWIW, my current Kindle is pickier about charging sources than any USB-C device I've ever owned. It absolutely refuses to charge via my alarm clock's USB port, which (with a USB-A to USB-C cable) will happily charge my headphones, portable battery, phones, and even my laptop (albeit very slowly)