I tried to build something much simpler than this.

For integration with cloud services you're going to run into OAuth, and guess what, that dance happens in a browser: get access to cloud drive -> get sent to provider login <<web>> page (or authorization page) -> get sent somewhere else.

I mean, you can build it without the browser, but a key and very early step involves a browser, you need it anyway. Might as well ship your own if you can do it.