Photos
Nextcloud provides a place to backup and manage your photos. There are two Nextcloud apps that interact with the photos and they each have thier strengths and can work with the same folder of photos. The Memories app is the best go to app and has fun features like a timeline. The photos app is better integrated with Nextcloud's file sharing system.
How to Use
There is a Photos folder in the Files app of Nextcloud. With that folder set as the root directory for the Memories app all photos added there can be organized into subfolders and albums within either photos apps.
Automatically uploading photos from devices
The official Nextcloud apps can be setup to watch folders and upload any new pictures to your Nextcloud Photos folder.
Memories
There are dedicated apps to view and interact with your photos in a modern interface directly on your device.
F-Droid
Apple App Store