>Make is generic. Nix is not. Before I even look at the actual code I already know that it is something I can use immediately on my existing system.

Hard disagree on this one. It's a series of makefiles that depend on apt (or whatever pacman you choose), so for any heterogeneous environment it's going to constantly be uphill battle to keep working in terms of package naming, existence of dependencies, etc. You'd find yourself reinventing Ansible, but worse.

> It doesn't matter how great nix is because it's not alpine or xubuntu or suse or freebsd or sco osr5 or solaris or cygwin, it's nix.

Nix runs fine on most (all?) modern Linux distros, macOS, even WSL, and there are workarounds to make it run on BSD, though I admittedly haven't tested those.

> Even if this thing has bash-isms and gnumake-isms, I bet with minimal grief I can still use it on a Xenix system that doesn't even have a compiler (so no building nix) but does have ksh93 and make, even without leaning on the old versions of actual gnu make and bash that do exist.

Use it on Xenix (which last shipped in 1991) to do what? The package management was tarballs and compiling. Instead of reinventing Ansible, you'd be reinventing pkgsrc. Not sure what your point here is.