It's similar, but not the same. The details matter. They're different because you don't need to deal with a complex abstraction layer to share logic. As in, you can expose an iOS Framework and call it from swift/Objc just like any other library. That lets you share tested logic and architecture, and do so optionally. It's not all-or-nothing. Xamarin is a different approach. Flutter is a very different approach.
Part of the issue when evaluating frameworks is expectations and not understand the plusses/minuses. If you are looking for a framework that will do 1 codebase for all logic and UI, without sacrificing any UX or capabilities, you'll probably be let down. Kotlin Multiplatform will be great for sharing logic and architecture. UI is somewhat of a different case. Why Xamarin wasn't great here is you need to do EVERYTHING in Xamarin, and write custom bridge code when not. It's an entirely different world, which bad IDE support for most of it's history. Jetbrains makes excellent tools, and if you understand that the UI will be "native", then there's a lot of efficiencies you can leverage here. If you get frustrated because you can't make one thing do all things, then yeah, it'll let you down.