Yabai[1] looks like it supports directional focus movement.[2]

You could also check out hammerspoon[3] and see if there are any sample configurations that could do directional focus.[4]

[1]: https://github.com/koekeishiya/yabai

[2]: https://github.com/koekeishiya/yabai/wiki/Commands#focus-win...

[3]: https://github.com/Hammerspoon/hammerspoon

[4]: https://github.com/Hammerspoon/hammerspoon/wiki/Sample-Confi...