[speedgoose]

Looks like Hammerspoon and some lua should do:

https://www.hammerspoon.org/docs/hs.mouse.html

https://www.hammerspoon.org/docs/hs.window.html

[bashinator]

Not seeing a way to get the window currently under the mouse pointer, but this is pretty interesting - thanks!

[speedgoose]

You can get the positions of every windows, the position of the mouse pointer, and you can focus windows.

[bashinator]

This is really cool, I'm gonna try and implement it!