It's not open-source, but I ended up using PhotoSync for myself and my wife to a locked-down samba share on my LAN .
They had a pretty reasonable (~$6) in-app purchase to unlock samba access, and the fact that it's a German GmbH means I'm slightly more confident they're not trying to copy all our photos to a dark data-vault.
Happy user so far, though it took some cross-checking against the samba share feel confident it was backing up reliably (I'm just particular about trust-but-verify :)
They had a pretty reasonable (~$6) in-app purchase to unlock samba access, and the fact that it's a German GmbH means I'm slightly more confident they're not trying to copy all our photos to a dark data-vault.
Happy user so far, though it took some cross-checking against the samba share feel confident it was backing up reliably (I'm just particular about trust-but-verify :)
https://www.photosync-app.com/home.html