There were few times that I regretted about lost photos:
- Micro SD card failure
- Kids playing around (especially with permission)
Finally, there came the idea to implement a kind of automatic synchronization from phone to a network-attached storage. Ideally, it should do its job in home network only, during charging. Luckily, I found a ready application for Android: Sweet Home WiFi Picture Backup.
The application requires a CIFS/SAMBA server in the network, so I installed it on the Raspberry PI 3, using Arch Wiki. And there it is, the cheap server with 32 GB storage, phones uploading their photos every few days when being charged, and the photos in safety.