(author here)

Thanks for the feedback!

I realize I wasn't actually using Google Photos, so my recommendation of hard drives likely isn't realistic for most people. TIL about Photoprism, I'll look into it.

For Google Drive, an actual solution for a typical use case would be something like Nextcloud (self-hosted or not, doesn't matter). My own use case was only about sharing a single file between two machines, so Syncthing fit the bill perfectly.

Again, thanks for sharing your thoughts :)