How to install Ubuntu Core zero touch from USB flash drive

How can Ubuntu Core be installed from a USB flash drive. I need this to be available so that a technician can install an image on a device.

Other container operating systems allow for this. One example is BalenaOS.

What would be the best way to go about installing a Ubuntu Core image on a device using USB flash drive in a “zero touch”/unattended way (except for changing boot device at startup)?