there's not supposed to be one and only "official" loading, where everything else is "side" to it
it's called installing programs
@navi me over here sideloading on NixOS /j
From a perspective of installing something on NixOS, it is in fact so much easier to do it using nixpkgs if its already packaged than any other way; IMO installing things on NixOS outside of using nixpkgs is more friction than "sideloading" is on Android, while using nixpkgs and the Play Store are similar amounts of friction
@navi eg debian defends this to some extent https://wiki.debian.org/DontBreakDebian
On Debian installing software from random websites is a bad habit. It's always better to use software from the official Debian repositories if at all possible.