Just to be very clear: the name "immutable distro" is unfortunately a misnomer. In practice, the restrictions found on so-called "immutable" atomic distros are very tame.

For example, on Fedora Atomic^[The atomic distro I'm most familiar with.], it's mostly a paradigm shift. That is, you can achieve (almost) everything that you can on a traditional distro, the only difference being how.

So, if we would take OP's query as an example, they are not able to do sudo dnf install vim btop. Instead^[Knowing that they're on Bluefin, a derivative.], they have to do brew install vim btop. Additionally, these changes persist, as you'd expect. Please note that this is just one of the ways/methods you can achieve this on Bluefin (and other Fedora Atomic derivatives). Other methods include:

• Install within a distrobox and export it.
• Simply layer it.
• Make a custom image that installs these by default and switch to said custom image.
• Install as a sysext.

As you'd expect, each one of these comes with its own set of tradeoffs.