Native GUIs, cross-platform backends

A while ago I saw an article that mentions how a macOS application had its GUI written in Cocoa/Swift, but the backend was a Racket JSON-RPC server: https://defn.io/2020/01/04/remember-internals/

This contrasts with what I did in the past, writing a Windows desktop application without splitting the GUI from the backend, completely in C#. Another nice aspect of this approach is that the backend can be reused between different OSes, as only the GUI is tightly coupled to the platform.