Technically I flashed the image directly to the La Frite eMMC with etcher on a Debian 10 laptop via USB2. Using the bundled USB male to male cable.
Upon bootup, I press (a bunch of times) Esc on the keyboard connected to La Frite, then after ~3 seconds (start pressing from turning ON the La Frite) I press down 5 times, then Enter and it appears on linux as "Linux UMS" a 8GB drive you can flash to.