I want to know this as well. My only interaction with a Kotlin Multiplatform app is Jetbrains Toolbox, and it's slow to start, has a lot of input lag and overall feels sluggish.

Jvm desktop is honestly the target with the best support. I always build on desktop during mobile dev first because I don't need to deal with connecting a phone or emulator. Second resizable windows by default is so helpful when building for many screen sizes. Also it has hot-reload now