Not naysaying you but i learnt kotlin and flutter this past year(from january). flutter has an AMAZING experience for the things that are "done", kotlin multi platform only does one thing well - kotlin.
it's basically like xamarin with C# swapped out with kotlin(and that sucks as much as kotlin mp does right now even after 3 years of ms acquisition time).
The development experience with flutter is great, that's right. But I don't like the end result. It feels very close to a native app but still not 100%. And I think it will always be a step behind.
One benefit of kotlin mpp compared to xmarine is, that kotlin mpp is not limited to iOS/Android. You can have a shared code base between web frontend/Backend/iOS/android and even macos/windows/linux and all native. One language to rule them all.
Flutter is on its way there, too. Already native on iOS, Android, and Fuchsia, with the web build in technical preview and desktop OSes under development.
I use C# almost on a daily base in Unity3D and have a little experience in Xamarine but I have no idea how a android/iOS/desktop/web project would be build up. Would be interesting to compare it with kotlin mpp.
it's basically like xamarin with C# swapped out with kotlin(and that sucks as much as kotlin mp does right now even after 3 years of ms acquisition time).