Installing a package shouldn’t break the keyboard. The keyboard is connected with an internal USB connection and should just act like a normal keyboard.
The thing about the uConsole is many of us users in this community are opinionated weirdos who heavily modify the desktop environment. I’m a little shy about giving step-by-step instructions for the uConsole because I’ve installed postmarketOS and am well off of the beaten path, currently running Musl and Wayland on Alpine instead of Glibc and X11 on Debian.
I did not run into the issue that you’re experiencing but I would recommend ditching the ClockworkPi image for the plain Bookworm Debian image that Rex put together. I think you’ll run into fewer issues. I’ve said before that I consider the ClockworkPi images more of a proof-of-concept than a proper OS.
Alternatively, you could add the repository you’re having issues with to your allow list. apt - how to install debian package from unsigned repository - Stack Overflow