[nextaccountic]

The developer experience must be evaluated holistically, because languages don't exist in a vacuum. The JS tooling, libraries and community absolutely impacts on how it feels like to be a Typescript developer.

The Kotlin situation isn't comparable because there is an established community that uses Kotlin in the backend, without using Android.

But perhaps you could compare with Swift: while Swift may technically run on non-Apple systems, that's not the experience of most developers. So it's totally valid to avoid Swift because you don't want to deal with Apple and Xcode.