The vacuum navigates and route plans based on the geometry, though, so chances are the actual map is on the device. Robot vacuums are competitive and plentiful enough to where there has to be one with a way to download the map from some endpoint on the device, or at least a way to pop it open and pull out some SD card. Of course, it’d probably be in a proprietary format, so transforming it into a usable mesh might be tougher than getting the data.
Obviously you just get an image, but for what I needed (map in home assistant with sensors overlaid) it was enough.