Meshcore seems to have an official map at https://meshcore.co.uk/map.html. Apparently nodes can be added to the map https://github.com/meshcore-dev/MeshCore/blob/main/docs/faq.md#512-q-how-do-i-add-a-node-to-the-meshcore-map but for now it seems as though that functionality is only in the proprietary app.
If possible it would be great to have this implemented in the open source app.
You may have to talk with the developers on Discord for this, and they might say no, and that it's only for the proprietary app, but we won't know unless we ask.