Earlier quoted context omitted.
> Unfortunately I needed a couple of things that were available only through apt. NixOS has approximately the same advantages, but a many times larger package repository. Take a look at that, it might already have your packages.
I'd like to point out that Guix is closer to ~52,000 packages than the ~29,000, as we maintain a bunch of things in separate channels that nixpkgs includes in its monorepo (e.g. the 20+k CRAN packages). See https://hpc.guix.info/channels and https://hpc.guix.info/channels/non-free for some popular channels used by HPC folks.
Just a few minutes ago, I decided to put off trying guix until later because it had fewer packages than nix, and was missing several that I need, that nix has.