NixOS has had the new `nix` command for a long while, this bundles up all the functionality under one command just like `apt` or `guix`. It's still marked as experimental and has to be enabled manually, but once done you'll never have to touch any of the old commands ever again. The only problem left is that a lot of the documentation still refers to the old commands.

> It is however a bummer that there's no socially-approved way to share packages of non-free software on the official channels

There is https://gitlab.com/nonguix/nonguix

That's one thing I prefer about NixOS, with Nix Flakes you can just turn any old Git repository into a package. No need to be part of any channels or need for the user to setup anything, you can just build and install straight from the upstream source with a single command line if they provide a `flake.nix` file. This automatically resolves a lot of pointless drama about what should or shouldn't be part of the distribution and makes it trivial to distribute patches and workarounds.