You’ve been able to boot Macs over a network connection for many years… here's an example using a Linux machine as a netboot server for a Mac: https://www.blueboxmoon.com/wordpress/linux-based-mac-bsdp-a...
The media I create require no network to boot. They only require 1. a computer with an appropriate USB or SD card slot that can boot from USB or SD card, respectively, and 2. sufficient RAM to hold the system.
This sort of usage is what I am curious about on the MacIntosh.