For porting maybe, but after the initial framework is released, new apps will just be built with both platforms in mind. Newer versions of UI Kit will probably

For porting maybe, but after the initial framework is released, new apps will just be built with both platforms in mind. Newer versions of UI Kit will probably shift people in the Apple Kit direction and then slowly deprecate all no compatible features. So unless app developers don't upgrade their app, sort of like moving to 64 bit, then yes everything would be a non trivial effort.