However, your reply gives me pause. The website says the apps are open-source, the other comment says the server is now open-source. Does that mean there's some pluggable black-box magic that the subscription enables?
To ask another way, if I self-host the server, can't I build the desktop app, import from Google Photos and then somehow export from the self-hosted server? Maybe not as ideal as a purpose-built script? Or is this not even possible?