Nix installs derivations into separate folders. A derivation can be a package, but can also be other things like configuration files, scripts or sources for packages. Nix doesn’t distinguish between these derivations by a name but rather by a hash created from their build instructions.
For example two instances of the same package with a different version are two different derivations and thus nix can have both package versions installed without them interfering with each other. But this goes beyond just a package version. It is e.g. possible to have the same package with the same version but different patches applied, or relying on different versions of dependencies. Since their build instructions differ both can be installed simultaneously.
This approach grants a variety of advantages. For example upgrading your NixOS system just installs new derivations of packages and configuration files that have changed, while keeping previous derivations until they’re garbage collected at a later time. This allows you to switch freely between both iterations of your system, for example if an update causes issues you can just revert back to before an update easily. Another advantage is that an unprivileged user can install packages they need without interfering with the rest of the system, for example an older python version or a newer one, or some software they want but the system does not provide.
The price of having this kind of isolation between packages is that nixos cannot install binaries and libraries into common locations. Effectively /usr/bin only contains the env binary. If you’re familiar with shell scripting you might have run into lines such as #!/usr/bin/env bash. This env util will essentially search bash in your PATH variable and start it. Lines like #!/bin/bash however will not work, because there’s no bash installed in that location.
Another case where a missing fhs is a problem is when using pre-compiled binaries. In contrast to binaries built through nix, which have their required libraries hardcoded as absolute paths, pre-compiled binaries you download usually only contain the name of the library they need, which works in a conventional fhs environment, because these libraries tend to be found in /libor /usr/lib. On NixOS neither of those are present. There two solutions to this. Either you create an fhs environment by listing the set of derivations to be symlinked into a chroot environment which mimics an FHS. Or you can install github.com/Mic92/nix-ld which automatically finds the required libraries the nix way if you start such a binary. There’s also steam-run which installs an fhs with most of the dependencies necessary to start Linux games from Steam.
Imho I wouldn’t bother with nix-env or nix profile. It just creates a secondary list of packages that needs to be maintained and it’s cumbersome to do so. There’s nix-shell or nix shell if you need a package temporarily and there’s your configuration.nix or flake for everything else.
Side note: nix profile at least has consistent commands: install/remove/upgrade
To be fair this is not the first infamous fascist with a bad hairdo, but this one certainly raised the bar. It looks like a bowl cut, but with different size bowls used…
First of all: Did you do apt dist-upgrade as well? If I remember correctly that is a new required step when upgrading to a new Debian release.
If that doesn’t help, you could check if your nvidia-detect package version is the expected version, that comes with Debian 12.
If neither of these steps help you could disregard nvidia-detect and try the steps listed in the following link. It seems the firmware was moved to a separate repository compared to Debian 11. You might need to add that by hand. wiki.debian.org/NvidiaGraphicsDrivers#bookworm-52…
Your i3 is too old. Perhaps your distro’s repository has a package called “i3-gaps” which was the former fork that implemented this feature. i3-gaps was merged back into i3 in the meantime.