Home Assistant user Anyuta updated their installation to switch map sources from Carto to OpenStreetMap (their blog entry on the subject: Alternative map provider for Home Assistant | Anyuta's personal blog) Unfortunately, this requires repeating with every system update.
I’m not sure I can improve on their reasoning - it’s a better map with more detail. It would enable instant import of POI data as zones near the home location or around any connected location source. It would even provide the data required to allow HA-local geolocation (for those with sufficient hardware) instead of depending on a location source using the Google API.
In short, changing the out-of-the-box map source would be the first step to bringing all the functionality of a standard GPS app (except crowd-sourced live data such as traffic) into Home Assistant and the Companion app.