I install or configure something every week.
In addition to doing the config, I'd have to edit a script as well, which seems like more hassle. At this point, why not go for nixOS and have just the latter part of the hassle without having to also edit config files in / ?
Instead, I run the backup command after I change something. When I want to restore, I can mount any of the last 20 backups from the borg repo and either manually revert a file or use rsync to mass overwrite.
I was thinking of using btrfs send, which would probably be even better for the purposes of recovering from disk failure, but borg file based backup takes way less space and works well so far. And I don't have the extra effort of a declarative os or setup scripts.
Also works offline as long as I am with my NAS unlike a script that installs a list of packages from the repos.