I know this an old thread but @
MrMars were you able to make this work?
My daughter has about 14,000 items on her phone (we previously backed up with iTunes) that we just can’t get up into iCloud photos. She is not home and on WiFi enough to make any kind of progress. However I was able to use her old phone before she traded it in to upload all her photos and videos on Amazon (took three days!). She is constantly at school and work so commandeering her new phone to get things in iCloud isn’t an option. My hope is that I can download her photos to the PC from Amazon and then upload them in batches to iCloud. Does anyone know if this will work? Or will we still be stuck in the “uploading 14,000 + loop?