If you use Waze, you can sign into the map editor and you'll basically see this. You can only edit where you've been so your editable area is kind of a fog of war
I contributed to OpenStreetMap when it was totally blank in my area and I was the only contributor. I used to let a GPS datalogger running and map every single trip. That was kind of like this. It was really addictive.
It's not fog of war, but if you go to the timeline and have location history enabled, you can see a map of all the places you've been. So if you're looking for new places to try out that's a good way to start.
It's because they don't do anything with your data, you aren't the product. Most people use this app over many years so when you factor all that in, it's worth it in my opinion.