Syncthing is an app for syncing files between two devices or between a device and the cloud. When you open the app, the option to add folders to be synced will pop up. The Camera folder pops up by default, which is where the photos you take with your device camera are stored. In the upper right part, you can add any folder you want.
In Devices, you can enter the ID of the device you want to add, choose the sync and compression type, or whether you want to stop syncing with a certain device. You can also add one or more devices to be continuously synced with each other.
The main idea of Syncthing is that you don't have to rely on the syncing services provided by large companies. Syncthing, is an open-source app that respects your privacy and data, meaning that you can choose where you want to store your data and whether or not you want to share it with a third party. In addition to this, you can even choose how they are transmitted over the Internet.
If you want to take control of your data, and decide how and with what you sync it, downloading the Syncthing APK is an excellent idea.