It turns out it's pretty easy to get maps in Notion. Notion will hopefully add a Github gist-like ability to edit maps in the code block (like they did with mermaid diagrams), but until then...
geojson.io | powered by Mapbox
Geojson.io can load data from a number of sources:
Hrk
Step one:
Use geojson.io to create a map.
Copy that code into a GitHub file or Gist
Such as https://gist.github.com/sgregson/383a7194f24f0dc4d2801cc34e47e274
Embed that into notion
https://gist.github.com/sgregson/383a7194f24f0dc4d2801cc34e47e274