And yet there's not much that's like native GUI paradigms in React.

At least when concerning all major GUI libs.

It's more like a markup driving an immediate-mode graphics API.

You basically just described Google's Flutter framework. It's currently only mobile but I see it moving into this space at some point - or already is I guess if you count Fuschia.

You can get it working on Desktop (I've got it on Windows with the help of https://github.com/ds84182/flutter_sdl and few other hacks, but certain things are missing - there is no support for mousewheel events, docking, or more than one window. Or keyboard input (though that should be easier to add than the three listed).

Thanks! Now I have something else to play with.

Components make me think in term of OOP.