I think kobowriter may be right for you, especially since it is made for your device.
The drivers and kernel are specially compiled by XCSoar project, which requires reboot.
The USB solution I was thinking of has been only confirmed on relatively newer devices.
https://www.mobileread.com/forums/sh...d.php?t=340418
The other idea was to use fbpad2 with an ssh/telnet connection to your phone/pc, and your keyboard connected to your phone/pc.
Install fbpad2 on your kobo.
On a ssh/telnet session to your Kobo (from phone or PC):
# /path/to/where/you/installed/fbpad2 /bin/sh
(and the keyboard input gets displayed on fbpad2 on the kobo.)
https://www.mobileread.com/forums/sh...3&postcount=11
(Different combinations of pc/tablet/phone/ssh/telnet may work better than others with USB keyboard.
But every combination I tried worked WITHOUT the USB keyboard, i.e. using just the phone/pc keyboard.)