How do NixOS users typically manage software that is not a Nix package, like a source code tarball where you would traditionally run configure && make && make install?
By writing a Nix package for it (I don't mean for this to sound flippant, tone is a bit hard to convey over text).
For example I have this alpha quality rust binary that I'm developing but I also want a stable version installed at the OS level. I write a Nix package and simply compose it into my overall NixOS configuration alongside the more official Nixpkgs: https://github.com/rraval/nix/blob/master/git-nomad.nix
> like a source code tarball where you would traditionally run configure && make && make install?
Nix has a bunch of defaults that make a conventional package like this straightforward.
Here's a package for a vanilla C binary + library that does the `autoreconf && ./configure && make && make install` dance: https://github.com/NixOS/nixpkgs/blob/master/pkgs/tools/secu...
It's almost a little misleading because the actual steps are largely inherited from the defaults, you can read more about `stdenv.mkDerivation` here: https://nixos.org/guides/nix-pills/fundamentals-of-stdenv.ht...
When it does, I either:
* build it via Nix, 10-15 lines, equivalent to packaging it.
* build it in a nix-shell that contains its dependencies
src = ./some-source-dir;
src = ./.;