@teh_g sadly, this won't be possible with Electron, since it requires V8, Chromium and Node.JS to run, all of which are not available on neither iOS nor Android.
You could maybe use Cordova for this, but it would require a C# developer, store licenses etc... not forget a great amount of time and effort.
Electron, on the other hand, makes developing Desktop applications with JS easy and really quick... So it would be quite easy to craft a NodeBB client. I imagine board admins could run an installer like npm install nodebb-electron-client-setup, then do npm setup and have the client available for download at http://example.tld/client/:os for their users.