> If a distro choose a build system to base their package manager off of, and you are on that distro when they make the change, their choice does not affect your use of another build system, unless your build system does not come installed by default, in which case, you install it and then continue as normal.

> But if your distro changes the init, you're in for a long period of relearning and retooling everything.

Depends on your distro's tooling and focus. At some point in the past, NixOS actually did switch away from OpenRC (IIRC) to systemd, supposedly without all that much fuss for end users.

On the other hand, migrating away from using Nix for builds would be a huge, huge deal and a big controversy to NixOS users.