CoMaps and many other projects just use OSM (Open Street Maps) for the maps. So it wouldn't be hard to make an wrapper interface and tie in Nostr if you know what you're doing.

OSM is usually updated by the users, so It's up to people to put the information in to the map. The editor is pretty easy to use, just have to make sure you follow the rules so the information is standardized.

I use to do a lot of Google Map editing, but they basically told all the editors to take a hike. Working on getting more things updated on OSM.