> It's also pretty difficult to package just the libs one needs when you are dependent on libc and other C libs.

It's pretty easy using Nix, e.g. this example defines a container for running a shell script: https://ryantm.github.io/nixpkgs/builders/images/ocitools

That script depends on bash, bash depends on libc, etc. so those dependencies (and only those dependencies) will be put in the container. (See https://nixos.org/guides/nix-pills/enter-environment.html#id... for an example of what dependencies look like in Nix).

> I suspect that if one was really ok with it, some tooling could be built to copy/link in system libs into the rootfs automatically from the host.

Eww, no thanks! I want my containers to be reproducible.