I have never used it in a moving vehicle for Mapillary, but the camera in my LG V20 has performed well in every other type of use I’ve made of it. It performs well-enough forward-facing that I considered using it as a dashcam, but ultimately decided to buy a dedicated dashcam instead, more to avoid excess wear on the phone than for any other reason. The V20 is also a powerful phone in general, and is the last high-end phone with a removable battery.
They can be had new old stock very inexpensively; or if purchased used in good condition, can be rehabilitated for the cost of a battery (~ USD $15.00 on Amazon). I don’t know about carrier and band support outside the US; but they are GSM, and unlocked versions are available.
This isn’t a recommendation so much as a hunch that it would work well, however, as I have never used it for the specific purpose you have in mind.
As for the GoPro Hero 5 and newer, the GoPro Android app is unstable, in my opinion; but the images are usable as taken using the GoPro Quik desktop client. They do have to be exported, but no further processing is needed unless you want to tinker with the images for some reason.
The Quik software is also a lot less problematic than the GoPro Fusion Studio software for the Fusion 360. (In fairness, however, I must say that the only problem I have with Fusion Studio since building a new computer is getting it to find the camera in the first place. Once it finds the camera, which can require quite a bit of prodding, the rest of the process is uneventful.)