> On windows(and I presume mac) these operations are tightly linked.

That's the default on windows, but it _does_ support focus-without-raising. In fact, it's literally called `Xmouse`: https://en.wikipedia.org/wiki/Xmouse

An easy way to enable it is to use Winaero Tweaker, but it's builtin Windows functionality: https://winaero.com/turn-on-xmouse-active-window-tracking-fo... (Just make sure "Enable window raising" is unticked).