Since that page has zero useful information on it, I found this elsewhere:

Depthboot is a builder script that creates a bootable USB drive/SD-card that can be booted on any x86_64 Chromebook. It supports common Linux distributions(Pop!_OS, Ubuntu, Arch and Fedora) and a variety of the most popular desktop environments. Due to licensing restraints, Depthboot cannot be distributed as an iso. Instead, it has to be build locally.

It appears to be a way to run Linux direct on device (non-ARM) instead of emulated, though I can’t be 100% sure since it doesn’t actually say that anywhere obvious.