Thanks, I've been emailing myself photos in Gmail 5-6 at a time like a caveman for the past several years... any app I tried was a non-cross-platform disaster or cost too much and had major feature bloat. This looks dead simple.
For SyncThing-Fork has better options for controlling syncing based on network, battery level, etc.
And then, at least on my phone, it rarely seems to goof up when the app starts the actual syncthing process. Syncthing-fork then just keeps showing "syncthing is starting up" on the status page and the battery drains quickly. It's still the best solution imo to have your photos reliably get backed up no matter where on this planet you are without resorting to Google/$PHONE_MANUFACTURER Cloud.
If you meant more freely aharing than that: apologies, misunderstood. But isn't that the problem Dropbox solved?