Iphone restore without backup

If you were syncing Photos to iCloud, you should be able to recover the photos if you sign into Settings/Your Name using the same Apple ID and turn iCloud Photos syncing on. The photos sync is extremely slow. It could take several days or more for the photos to sync.

Try Settings/Your Name/iCloud and slide off syncing. Wait a few minutes and then slide syncing on. Allow time for syncing to occur. The photos sync is extremely slow. It could take several days or more for the photos to sync.  

Last resort - have you tried signing out of iCloud, restarting the device, and then signing back in?