You will notice that it is surprisingly simpler than React.
React got so popular because React implemented it very nicely in the web browsers, not because it brought new concepts.
When using C++, looks like you have to use things like QAbstractListModel https://qmlbook.github.io/ch16-qtcpp/qtcpp.html#a-simple-mod...
Even without C++, there are things like ListModel and ListElement https://qmlbook.github.io/ch07-modelview/modelview.html
This is a far cry from React where you just use language-native data structures directly (you only need to do mutations in specific ways).
As far as I can tell, you also can't just use native language constructs like functions/ifs/.map, etc. to compose the UI elements. Instead you have containers like Repeater.
It seems very different to me compared to React, like built around a significantly different philosophy.
Even defining what a "native" type is seems like it would be fraught. I guess the c++ way would be to accept begin and end iterators - but of what type?
When I imagine how a C++ implementation of something like React would look, my first thought is a bunch of functions which take whatever custom types they need (props), and return a tree of UI primitives (analogous to DOM element representations). Nothing that would require inspecting types.
Think about it. How do you iterate the tree? What even is a tree? The typical c++ answer depends on templates and iterators within the template. Which means they wildly change at compile time. It is clumsy for a shared library to deal with this, or, say, bind properties from an XML file or similar parsed at runtime.
Hence, it would make sense for a c++ solution to impose its own format or base class for trees or models. (Perhaps a template could help to wrap it.)
There may be some limitations and some things may need to be done differently because of C++, but from a brief look it should be basically possible. The UI library doesn't need to iterate through props, those can be a single opaque structure from its point of view.
I tried doing something similar in Kotlin a few years back and from what I remember there wasn't any reflection used for that part. https://github.com/peterholak/mogul
I'm also still not convinced that Kotlin/Native will catch on in any significant way, but we'll see.
WPF still has the same kind of approach and to be terribly honest, Silverlight, as hated as it was, did it before React.