The easy way:
1) save the 4000x2000 image to iOS camera roll
2) upload to RoundMe.com
The more viewable way:
1) save the 4000x2000 image to iOS camera roll
2) find an Exif editor and modify the following
A) Make: “RICOH”
B) Model: “RICOH THETA S”
3) upload to Facebook and it will recognize it as a 360 sphere.
Sadly DJI strips off all Exif metadata from the 360 images. Even if they didn’t, I don’t think Facebook has DJI make/model always tagged as 360. The better solution would be for DJI to add Exif XMP tag, "ProjectionType=equirectangular" and we wouldn’t have to do anything.
Here’s my source data:
https://facebook360.fb.com/editing-360-photos-injecting-metadata/
P.S. I use
https://itunes.apple.com/us/app/photo-data-by-exiƒ-photos/id992313925?mt=8 but it’s not free.