Recently I wanted to make a Kotlin version of my neovim-java library. Idea was to make it possible to use for any of available Kotlin targets, which will make it significantly harder to develop.
Check out progress at neovim-kotlin. Before this is possible, first MsgPack support needs to be implemented, since it is not available in kotlinx.serialization, so I also started work on kotlinx-serialization-msgpack. All of this will take some time, since I only have experience with Kotlin on JVM.