[howinteresting]

I'm not sure what you mean then. Clearly you have to put a bunch of effort into building tooling that works on Windows, and Nix won't cut it for that (you must build on Windows in most cases rather than cross-compiling). And if you're doing that you might as well also reuse the same tooling on other platforms.

Nix flakes can still be useful on the tool user side, if your application build requires Unix anyway, but on the tool producer side it's a bit less so.