Partially true, HarmonyOS NEXT is its own thing, with a Typescript based language ArkTS.

https://developer.huawei.com/consumer/en/arkts/

And now they are adding yet another one, AOT compiled, Cangjie

https://cangjie-lang.cn/en

Using Android fork has been a transition step.

Neat, thanks for this correction! Interesting, an entire new programming language.