> core logic in a cross platform language and native gui code
This produces a superior (often vastly superior) result, and it's also very hard and time-consuming.
As an example: for Apple platforms only, SwiftUI can enable you to write a high-quality macOS/iOS/iPadOS app, but the devil is in the platform-specific details and exceptions to the generic behavior. Even Apple doesn't do a great job with some of its own cross-platform apps, and that should tell you that it isn't easy and doesn't come for free.
Now consider the effort to get that level of performance, usability, and platform integration in a "non-native" framework that also targets Linux/Windows/Android/etc..
This produces a superior (often vastly superior) result, and it's also very hard and time-consuming.
As an example: for Apple platforms only, SwiftUI can enable you to write a high-quality macOS/iOS/iPadOS app, but the devil is in the platform-specific details and exceptions to the generic behavior. Even Apple doesn't do a great job with some of its own cross-platform apps, and that should tell you that it isn't easy and doesn't come for free.
Now consider the effort to get that level of performance, usability, and platform integration in a "non-native" framework that also targets Linux/Windows/Android/etc..