you need to apply the mpp plugin in

ios.gradle.kts

as well

I tried

apply(plugin = "kotlin-multiplatform")

before the import statement, but I get the same result

I believe so. You could also try

plugins

notation, like “org.jetbrains.kotlin.multiplatform”

after reviewing kotlin gradle dsl docs, looks like it's too early to switch to kotlin build gradle for this situation. afaict, you don't get type-safe accessors in applied scripts like this