As an experiment, I logged out from my Kobo account on one of my devices, let it do the reset and then, when prompted for language selected English and said No to the WiGi. The device then displayed the connect to my desktop and install Kobo Desktop message.
I made sure that neither calibre, ADE or Kobo desktop were lrunning and connected the Kobo to my PC.
I then launched a Sqlite client (in my case DB Browser for SQLite
https://sqlitebrowser.org/), opened the Kobo database and did the SQL command I mentioned above
Code:
INSERT INTO user (UserID, UserKey, UserDisplayName, UserEmail)
values("00000000-0000-0000-0000-000000000000","00000000-0000-0000-0000-000000000000","MyDummyUser@dummy.com","MyDummyUser@dummy.com")
When I closed the database and ejected the device it proceeded to import all the sideloaded content I had on the kobo.