If you use F#, Fabulous[1] for mobile apps and Fable+Elmish[2][3] for web exist. I use Giraffe's[4] view engine for server-side HTML templating. And it looks like AvaloniaUI is going to have a similar style UI in FuncUI[5], but I'm not sure how active that is.
I'm not sure about any C#-focused efforts.
1: https://github.com/fsprojects/Fabulous
2: https://github.com/fable-compiler/Fable (transpiles F# to JS)
3: https://github.com/elmish/elmish