AFAIK SwiftUI is derived from or inspired by The Elm Architecture.
In any case for me, Elm has been extremely enjoyable, as a web frontend framework and language combo.
I am a huge Elm fan, and I have used it in many contexts. It is fair to say that in the last 10 years React has most influenced the way we write our UI and Elm has most influenced the way we manage our state on the frontend.
An alternative would be Dart/Flutter, though I’ve heard web UI perf is awful atm.