Hey @serviteur! That sounds like a fun and challenging project to tackle.
I too am running a project map at the moment and have found that the free add-on Blender GIS is amazing for giving you a solid base. If you don’t necessarily need it to be a modular/expandable setting (like with Geo Nodes and BCity), that might be the way to go.
Here are a couple of videos that might be helpful to get you the idea of what it can do:
https://youtu.be/YNtKnmRXVlo?si=l2xN8kWrlrTKfeuA
https://youtu.be/Mj7Z1P2hUWk?si=2kCpyCBubg6Lai1P
Then, there is the open source QGIS software, that will give you an easier time if the are you need is too much bigger. Though for the looks of your map, Blender GIS might be just fine for great amount of detail.
https://youtu.be/1GveI7knDuA?si=wvlVleH7uGQ7U5le
With Blender GIS and Google Data, one word of caution for commercial projects though. Read their licensing terms and make sure they apply to you. The OSM maps are totally fine to be used, but if you choose to bring in roads/buildings/ and more… just check what can and cannot be done commercially.
Hopefully this helps a bit, or sparks some ideas.
As for your other questions, I’m not sure how to help. Curious to follow this thread though.
