What is wrong with the fork from F-Droid? I use it. I see no difference with the original, I’d say it’s even better. If you don’t trust them for some reason, why discard Syncthing as a project? I assume it can be built then. But I have no idea how.

By the way, I’m happy to use Sushi Train on iPhone. Works very well, and is lovingly polished. Now Syncthing is a centrepiece of my workflow to sync my files.