We use Google Maps for our global chapters map, but let’s improve that by using OpenStreetMap. Leaflet is something that may be used to create a custom overlay (there are probably other ways as well).
I won’t pick this up now. But in case someone from the @it-team thinks this is a nice project, then please feel free If you want to work on this, then please let me know. Then I’ll assign you to it.
There is also a Leaflet Discourse plugin, but it’s not an official plugin. For stability/security reasons I want to stay away from those plugins.