What I like about Kotlin Multiplatform (KMP) vs Flutter is that KMP is not a framework. For instance, I can write a KMP library and a "pure" Android or iOS app can pretend it is a "pure" Android/iOS library.

That is, pure native apps, can integrate KMP libraries. They cannot integrate Flutter libraries.

In other words, if I write a KMP library, I can ship it for multiple platforms and developers can use it in their Flutter project, or in their pure Android/Kotlin project, or in their pure iOS project.