How do I confirm an iOS device has uploaded/synced all photos+videos to iCloud Photo Library?
Details
I have yet to find a way to determine explicit status of the iCloud upload/backup/sync similarly to the 'Backup complete' explicit status that the Google Photos iOS app provides.
I can login to iCloud.com and see what photos/videos exist, and hope that, if the latest-dated photo/video on my iOS device is also found in iCloud.com, that all the photos/videos are saved in Cloud. However, this would not account for the iCloud Photo Library syncing the photo/video files "out of order" (like Google Photos seems to do, apparently syncing the largest photos/videos last).
For my immediate purposes, 'iOS device' = iPhone8 running iOS 11.1.
EDIT
I notice now at the bottom of the iOS Photos app this status:
However, the upload has seemingly been stuck on '217 Items' indefinitely, even while connected to fast Wifi (speedtest.net-tested to be 10+ Mbps upload) and while the iPhone8 is externally powered. I also power-cycled the iPhone, and no change in behavior. I added a photo, counted incremented to 218, then quickly when back down to 217... and stayed there. What gives?

https://apple.stackexchange.com/q/336356/13179
– Johnny Utahh Sep 14 '18 at 02:00SE can of course do what it pleases. It will do it with less contribution from me.
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Thank you for everyone's contributions.
– Johnny Utahh Jul 11 '19 at 14:24