I also have very minimal dotfiles. Less than 200 LOC in total, including whitespace.

They have barely changed in the last decade. Two key things to be able to work like this were:

* Moving most of my computing to 3 platforms (Emacs, Unix and Firefox). I don't use any GUI application aside from a manual tiling window manager.

* Migrating to a barebones distribution, Arch / NixOS. A small half a page imperative / declarative script is enough to configure all my system.