You're right: PhotoStructure for Desktops is currently packaged with Electron, but I'm not happy with how heavyweight it is. I see it as a way to "kick the tires" and a way for my Grandma to run it without opening a terminal.

PhotoStructure for Servers has two flavors: a docker image that's based on Alpine (it's a ~300mb image and typically takes ~30mb RAM to start), and, if you're more comfortable running Node directly, you can git clone the repo that the docker image is built from and run directly.

Imports are slow on an RPi (it's about 1/4 the bogomips of my decade-old MBP), but the UI is quite snappy. This is because the import front-loads all the computationally expensive work, like metadata extraction, inference, image resizing, and video transcoding.

Also: Libraries are both cross-platform and cross-edition. Start importing on a Mac with Desktop, rsync the library to your NAS, and continue with docker.