smexy how much space do you have available on your device and system?
Also just because the cable can unlock the bootloader doesn't mean it can communicate via fastbootd at low level. Is the cable the one that came with the device? If not many brands cut corners and don't fully comply with the standard.
Belkin Anker and Aukey are known good cables.
If that doesn't work using the stock pixel C-C cable try an Android to Android flash if available using another phone with USB C.
Also be aware that using USB C on a laptop or front IO often doesn't work due to implementation method. Connections should be direct to motherboard on desktop and using A-C on laptops.