I would like to mention Svelte specifically. It's a different approach than React/Karax.
But it's well worth to watch [talk of Rich Harris](https://www.youtube.com/watch?v=AdNJ3fydeao) creator of Svelte why it created it and how it works. And maybe go through [Svelte Tutorial](https://svelte.dev/tutorial/basics) it's interactive, simple and very well done. I think there could be ideas in Svelte that could be applied to Nim Reactive UI, given that it has rich macro capabilities. They say Svelte is faster than React, it's true, but I personally don't care about the UI speed. Modern computers are so insanely powerful that's pretty much impossible to slow it down with UI, unless you do something really wrong or write heavy animations like games. Svelte is not only faster (which as I mentioned already is not that important) but also simpler and more productive than React. And it feels like that approach could blend well with Nim.