Using git as an example:
- package is installed globally: https://github.com/matklad/config/blob/42342dd9d25b2105fdf3786846157e2309706e75/hosts/default.nix#L100
- configuration is stored in the same dotfile repo: https://github.com/matklad/config/blob/42342dd9d25b2105fdf3786846157e2309706e75/home/.config/git/config
- it is symlinked to
.configby a script: https://github.com/matklad/config/blob/42342dd9d25b2105fdf3786846157e2309706e75/xtool/src/main.rs#L74