my usecase would be :
buy book (kindle) - download directly onto eink reader over ethernet via usb-c (no sideload involved) - kindle naturally in airplane mode - for offline reading.
previously , used various methods, too , for achieving internet over usb, when usb-c was not such ubiquitous connector;
like with this here
https://github.com/Genymobile/gnirehtet
but nowadays, most tablets and phone allow for ethernet over usb(c), just some apps don't allow for downloads other then on wi-fi.