When comparing Nix vs Tails, the Slant community recommends Tails for most people. In the question“What are the best Linux distributions for desktops?” Tails is ranked 31st while Nix is ranked 65th.
Ranked in these QuestionsQuestion Ranking
Pro No side effects when building packages
Nix is a purely functional package management system. This means that the act of building a package does not have side effects, such as destructively updating or deleting files that may be used by other packages.
Pro Isolated development environments
Nix allows the creation of project-specific shell and build environments which are isolated from the rest of the system. These environments are defined declaratively to ensure reproducibility.
Pro Can replace docker in some places
Pro Can use multiple versions of the same package
Because of the functional approach it takes, Nix makes it easy for systems to use multiple versions of the same package simultaneously, and ensure that updating or removing a package can't break other packages.
Pro The configuration works on "All machines"
No more of the traditional: "it works on my machine". When it says reproducible, this is the real deal.
Pro Privacy focused
Pro Has TOR built-in
Use the Internet anonymously and circumvent censorship; all connections to the Internet are forced to go through the Tor network.
Pro Easy to use with an USB key
Con Does not work well for services on non-NixOS systems
When using Nix with anything other than NixOS you can run into difficulties with trying to start up services. For example, you can install docker with Nix, but it won't integrate with the host system's systemd leaving you to handcraft awkward workarounds in order to start the background service that docker requires. This seems like a critical flaw when using Nix on anything that is not NixOS, and it's unfortunate because this affects many of the packages many users would be most interested in using Nix to handle.
Con Steep learning curve
Con Cannot handle filetypes that have different semantics across different versions
While the functional approach that Nix takes is great for sandboxing binary artifacts of packages, it seriously lacks any power in handling configuration files or user data. It's difficult to upgrade and downgrade files where semantics and syntax can change between versions. Especially in Debian/Ubuntu it can cause severe problems where the upgrade process blocks and the user needs to resolve the 3-way merge.
Con Feels slightly over-complicated
Con Not for daily use
Tails is a privacy focused Linux distro. The updates that you will receive are only for improving privacy and not for improving user experience.
Con You can't install it to a hard drive
Con Saved states are not present for security
For security reasons, saved states are not supported in Tails. Files can be stored in a separate, persistent volume which must be accessed with a root password. Personal settings (e.g. -- keyboard layout, window settings, etc.) are not saved persistently across reboots. This can be a hindrance for anyone not using English as their language, or not using a QWERTY keyboard layout.
Con Only GNOME desktop environment
Con Slow internet
Tails uses the TOR network and as a result the internet on your computer will be very slow.