I’ve been using GPUI in a side project of mine (TukeySheets.com) and can attest that it is quite nice and it works well on all platforms, at least in my experience. So I would say, definitely “we are gui” in rust.

The component library by long bridge is also well done and reasonably well documented.

That looks very nice. How much of the UI is effectively stock gpui-component vs custom components? The charts? I assume you did custom theming?