Maybe he could try again with Jetpack Compose for JS? Then he can use his Android knowledge for the UI and there is less complications with bridging Kotlin code

Maybe he could try again with Jetpack Compose for JS? Then he can use his Android knowledge for the UI and there is less complications with bridging Kotlin code in JS/typescript. To be fair though, Jetpack compose for web is quite new so there is not yet a big ecosystem.