You know, you can't just say "anywhere". User interfaces are used on microcontrollers, on embedded systems, on legacy systems, on odd platforms, on old platforms. Rust certainly doesn't target all of those, or even most of those, and not even many of those.
Even statements like, "One codebase, every platform" are just... wrong.
And if they were right, would have so many compromises nobody would use them: we have different platforms because we have different constraints, and that percolates up to the interfaces.
Even statements like, "One codebase, every platform" are just... wrong.