Earlier quoted context omitted.
Plug in a phone, run adb pull /storage/emulated/self/DCIM or wherever that Android garbage OS stores photos these days. Local, doesn't need encryption since there's no middle in E2E that you need protection against, and simple. Grandma can setup ~/.zshrc `alias bak=cd ~/phonephotos && adb pull ...` to make it even simpler.
When I'm done teaching grandma shell scripting, I'll let you know
You're way too slow at teaching...