I saw on GitHub that somebody posted a PR to fix the patch that blocks firmware updates:
https://github.com/pgaskin/kobopatch-patches/pull/137
The patch targets a link to api.kobobooks.com to stop the firmware update check from working.
The notes in libnickel.so.1.0.0.yaml warn that the patch is dangerous, as it can cause a boot loop if you do a factory reset. If we know what the update URL is, would it be equally effective to redirect api.kobobooks.com in the hosts file to block firmware updates without the bootloop risk associated with the patch, or would that cause negative side effects? The only reference to api.kobobooks.com in libnickel.so.1.0.0 seems to be for the update check.