Comment by rav

It seems to me that macOS has env -S as well, but the shebang parsing is different. The result is that shebang lines using env -S are portable if they don't contain any quotes or other characters. The reason is that, running env -S 'echo a b c' has the same behavior as running env -S 'echo' 'a' 'b' 'c' - so simple command lines like the one with uv are still portable, regardless of whether the OS splits on space (macOS) or not (Linux).