While viewing an album in iOS Photos, I selected about 50 photos and used the share-sheet service to send them to a new album in Flickr. After confirming the share, I was returned to Photos, and as far as I can tell, there’s no way for me to determine the progress of that share, other than visiting Flickr, and reloading the album page until it reports containing 50 photos.
Furthermore, if I leave the iPad unattended, it appears the share progress will get terminated when the auto-lock timeout triggers, requiring me to start the share again after figuring out which photos made it the first time, and which didn’t. (And that, in itself, is quite a challenge as the upload order is seemingly random!)
Until this is improved, it seems that when initiating such a share, I’d need to sit and continually tap the screen (keeping the device awake) until the share concludes.