Thanks everybody for your help.
Bought a libra 2, quite happy with it.
In case some people read this thread later, you can indeed use the ereader without having a kobo account or installing any software, just connect it to a computer via USB and change this config file (on the top of the image you see the path of folders you need to follow for finding it) and setting SideloadedMode parameter to true (or adding the whole line if it doesn't exist there already). Eject the ereader from the computer, shut it down and turn it back on. You should be now in the main menu (granted, some features of the device require to log in, but that doesn't bother me much)
