Very cool! Noted on the Vietnam camera manufacturer connection. Feel free to PM me if you would like to share some details. In general the GoPro MAX is quite good at most of what is required for Mapillary, and we will work on improving the upload process in desktop uploader per your suggestion. In terms of evening recording, it would be best to avoid it, as signs, etc are always harder to read in lower light (even though city night life does look cool) 
Thanks for the feature request on Geo tracker. In the latest version of the Android app (Updated Android app design: What do you think?) you can toggle the “color by date” feature which will show you areas of the map that have new vs old captures (new will be green). It’s not quite the same thing you’re mentioning here, but might also be useful to you.
All the best!
- Boris