currently networkmanager is above >400MB, because we include a lot of unneeded modules. there is a pull request on github.com/nixos/nixpkgs (#84433) which tried to tackle this, but was needlessly complicated. A simple list with just the needed modules would probably suffice.

there is now a PR open: [#140666](https://github.com/NixOS/nixpkgs/pull/140666)