How can I preinstall Endless?

I would like to preinstall Endless for a costumers. How can I do it?

Boot from the live usb and choose “reformat” when asked.

Wait for the process to complete. Eta ~15 mins. Turn off the pc and remove the usb stick.
Setting up system locale, keyboard input, username and password will be asked on first boot.

One way to do it is leave above options to the customers (guess they can read? it’s not that hard imo) or setup a generic username and password and give that away seperate.

Such as User:Password1234. Not a good combo, only giving an example.