Like a number of other people, I'm motivated to gradually replace all of the device-specific AC/DC transformers in my life with USB power delivery.
I eventually intend to design and build a multi-port USB power supply which I can use instead of a huge power strip to do AC/DC conversion only once and power many devices.
First though, I'm working on this simpler project in order to get more familiar with the details of USB C Power Delivery: a small adapter that has a USB C power sink on one side and a typical barrel jack on the other side, with a chip in between to handle the USB C PD protocol.