I’m trying to word this carefully, but to be clear I am looking our for your best interests here. If doing things the way @tejing is suggesting seems unappealing, then you are not going to enjoy using nix/nixos, and that’s ok.
Nix is all about packaging everything and once you get the hang of it, banging out a derivation to wrap some script is not a significant time sink. OTOH, if not using nix leaves you with zero dependency problems to solve and all you’ve been burdened with by using nix is extra work, why bother? Just use something else more suited to your workflow and needs.
Everyone here obviously thinks nix pays for itself, otherwise we wouldn’t be using it. That doesn’t make this community correct of course 