Like Tauri, this is only lightweight in terms of download size as it doesn't download chrome. The 'bloat' of electron is really at runtime due to loading a full browser engine. Both neutralino and Tauri will use roughly as much ram as an electron app, give or take. You're only saving on download size.
This is only the case for Tauri on Windows because the native website is just Chromium. On MacOS it’s much leaner. I can’t find the thread where the Tauri devs mentioned a plan to fix this, but iirc they do have one.