I get Docker-actual reproducibility with Fedora Silverblue and toolboxes. Enter one of my Arch/Fedora containers, install Calibre without affecting the host. Even better than Nix because I can test custom distributions, rather than each environment simply being another NixOS.

In fact, I've departed from vanilla Silverblue, as now my base image is an actual, bona-fide Docker container as well.

I feel like the immutable Linux OS is the pragmatic approach, whereas NixOS is the pure, ideal way that requires a lot of changes to tools and workflow to work. Maybe even in this case, worse is better.