would be great to offer a standalone app version of Lumo, like the Proton Mail app or Proton VPN

Right now, it's the only reason I wouldn't use Lumo. Since it runs only as a web app ALL keystrokes are able to be logged in browsers like Chrome, Brave, Firefox, Safari etc. what does privacy mean? If the browser you have to use to run Lumo, literally logs all keystrokes?

A full app could offer so much better customization, or some local model possibilities and integrations like from another story. Right now, Lumo seems decent but I wouldn't use it when it's hosted in a browser still. Totally defeats having it Privacy as Default