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(including 360° imagery that needs stitching).
May I recommend “Hugin”?
This most likely is perfect for Mapillary!
It is a universal stitcher with the option to stitch via command line. One needs a PTO file (a configuration file) to do a good stitch… and if you can’t find a PTO file on the internet (or the result isn’t good enough for you)… I could help creating one (did so for my YI360, and I’m quite impressed with the result as you may have noticed in other threads 
).
The stitching is quite time consuming, so if that could be done at your end… I’dd be quite happy with that!