It varies widely based on the type of app. Most simple apps using standard lib or a few basic crates/packages/gems/etc can indeed be switched over without too m

It varies widely based on the type of app. Most simple apps using standard lib or a few basic crates/packages/gems/etc can indeed be switched over without too much fuss. But if you're using any large frameworks with a ton of dynamic features that dictate the structure of your application, such as Rails or Django, then it's hopeless, it'll need a complete rewrite with major architectural changes.