Home-manager: selective update of packages possible?

I use Nix with home-manager (unstable channel) on several Debian machines for about two dozen packages which do not exist/are too old in Debian.

In january, home-manager switch failed due to a bug in one library. That’s fine, I understand what ‘unstable channel’ means.

But I realised that I do not know how to update selectively some of the packages not affected by the bug. If I comment packages out in home.nix, they get deinstalled.

Is an update of single packages possible with home-manager?

You can add a new nix-channel (e.g. nixpkgs-newest) which you update. And than use the package you want to update from this channel

You can do that with the nixpkgs.overlay option. See the second example on Home Manager Manual

Or just add it to home.packages like so

home.packages = [
  (import <pkgs-newest> {}).new-package

Ah, so you can define your own channels. Thank you!