Comment 17 for bug 1943124

It was not an option to keep my system broken for longer, so I mounted my system disk to a working Ubuntu installation and used 'dpkg --root=/mnt --force-script-chrootless -i ...' from there for getting libc installed, after which a native apt install -f was able to take it from there.

Let's hope that this was really really a one-off error nobody else will see because I will not be able to provide any further information with something like 1500+ packages now having been upgraded.