As far as the networking function, I've had a variety of situations over the years where SOME kind of basic photo management that didn't rely on an external server would have been very helpful. Usually corporate networks where Google Photos is banned and nobody understands why our *current* file server can't do that. It still echos in my head: "but it's SharePoint! It has loads of features for pictures!"Hydrus organises your files into an internal database and browses them with tags instead of folders. Tags and files can be anonymously shared through custom servers that any user may run. Everything is free, nothing phones home, and the source code is included with the release. It is developed mostly for Windows, but builds for Linux and macOS are available (perhaps with some limitations, depending on your situation).
License: WTFPL (the anti-license)
Resources: the program itself is massive. For a photo tagging/viewer program you're looking at 500 megs.
Status: Portable. As noted above, I didn't test the program thoroughly but initial checks seem to suggest all changes staying local.
https://hydrusnetwork.github.io/hydrus/ ... ction.html
https://www.softpedia.com/get/PORTABLE- ... able.shtml