You no longer need to edit the database. Connect over USB and edit .kobo/Kobo/Kobo eReader.conf. Find the [ApplicationPreferences] heading, or create it if it doesn't exist, and add SideloadedMode=true to enable sideload mode. Eject and reboot, and you'll be able to use the device without a Kobo account.
If you want dictionaries, you can sync or use this thread to download them directly:
https://www.mobileread.com/forums/sh...d.php?t=346645
I don't know if you can do the notebook setup without syncing, but syncing once for dictionaries and notebook setup shouldn't be a big deal. You can keep Wi-Fi off after that, if you want. You can get firmware updates over Wi-Fi or install them manually over USB.