There used to be a Palm OS app called CityTime that combined world clocks and twilight/night areas on a 2D map: https://palmdb.net/app/citytime

This is a webpage that has a clean map visualization: https://www.timeanddate.com/worldclock/sunearth.html

Here is another: https://in-the-sky.org//twilightmap.php

EDIT: Vibe-coded another: http://nixon-development.com/worldclock