Having a map-making tool has been suggested before, but I don't think it hurts to bring it up again. It would be right up there with the timeline tool that's been being discussed here recently, in terms of usefulness.
Actually, if/when we get both of those, it would probably be nice to be able to connect them. Like, have a layer that you can turn on/off for each timeline you have, and, if you have an event connected to a location on the map, it shows up as a little icon. I imagine it looking like a little bubble with a picture (if applicable) and the title of the event.
As for how the actual map tool would work, there are various map-making tools around the internet already with similar capabilities. Inkarnate comes to mind, and I've seen a post on the worldbuilding subreddit about a map-making tool someone's working on called GenBrush. I'm sure there are others, as well. So, yeah, it's definitely possible, though, I'd probably make it a separate tool, rather than embed it in the 'Universe' page. Maybe under the same category as the Documents and the Prompts tools, and maybe rename that category to "Tools," if so.
Even if there wasn't a "Paint the map yourself right here" type of tool, you could probably at least upload an image of one you've created yourself. Or, if you're creating an Alternate Earth, it might be handy to have some sort of way to use an editable version of Google Maps (maybe you select the area of google maps that you want, and then the sight basically converts that into a screenshot/jpeg thing that you can edit).
From there, it might be handy to have layers. The base map, of course, and then layers like biomes, where you can paint them in over your land masses. For uploaded images of maps, there could probably be some sort of sensor or 'magic wand' tool like there is in image editing software to identify land vs. water quickly. On top of that, you could have a political map, where you can paint country boundaries, similar to the way you'd paint biomes. I don't know much about coding, but I imagine you could probably make a way to do this with already-created pages, so that when you clicked on the country, it would bring up a little sidebar-version of that page on the right, or perhaps just bring you to the page itself, if you're on mobile.
In addition, you probably also add a 'places of interest' sort of feature, where you link various pages to various locations (like buildings, locations, towns, governments, groups, characters, etc), which would show a little icon similar to the ones shown on the 'timelines' layer mentioned earlier. Perhaps (maybe this would be a premium-only feature, I don't know) you could even embed maps within maps. So, if you have a big world map, but then you have a more detailed map for a certain city (or even part of a city), you could put the more detailed map in a special field within that place's page, and then the marker for that place on the map could have a little 'zoom in' button or something, which takes you to the closer map when you click on it/tap it.
The only other feature I can think of that might be helpful is the ability to filter various items, similar to how you can filter pages now, so that you only see what you want.
For all this to work, I'd imagine you could have a separate toolbar on the right, with different pages for different tools/features or something like that.
Anyway, point is: A map-making tool would be very handy. I kind of got carried away, sorry. I tend to do that. Whoops.