On mobile, it used to be hard to build beautiful cross-platform apps. Then React Native came along, giving us a seamless way to build user interfaces and manage state in code, all while doing it cross platform.
On desktop, there is no such tool. You can create a GUI using something like Qt, but for people who are used to the React workflow and JSX, there currently isn’t an alternative.
Some of you might be saying that you could do it in Electron. It’s a good tool, but it brings in a lot of overhead, running a full webbrowser to manage a small GUI, while Proton Native can do the same, using native tools, with a smaller size and with less resource usage.
Proton Native does the same to desktop that React Native did to mobile. Build cross-platform apps for the desktop, all while never leaving the React eco-system. Popular React packages such as Redux still work.

Source: Home – Proton Native – React Native for the desktop, cross compatible