I write primarily Kotlin for a living currently and have for several years.

Despite having a positive relationship with the language, I don't think it's the best choice for multi-platform UI apps.

If you want to be pragmatic about it, you just can't beat React Native. The ecosystem and tooling are an order of magnitude larger, the DX is better, and the talent pool is also an order of magnitude larger.

KMP on Desktop/Browser are also comparatively lacking, with browser having split development between Kotlin.js and the new WASM Skia backend.