Imo it's the opposite. Since the system is defined in config files, an AI agent can look at live system state/errors vs. the config file and do all the work of figuring out the issue.

Also, using higher level modules like home manager makes things more declarative and less fiddly since someone else is maintaining the lower level.

Maybe nix is a downgrade for what you do. But I loved nix so much that I also migrated to nix on macOS (nix-darwin). No more homebrew.