Some might argue that this is intentional, but to me, this more likely shows that HarmonyOS is just a hard fork of Android without sources released and, likely, with their own virtual machine implementation (ARK instead of ART).
Looks shockingly similar to Android Studio including the exact same program layout on the filesystem and SDK compatibility selection.
ArkTS itself looks new enough, but if it turns out to just be something like Flutter, running on an otherwise Android OS, that doesn't look like it would be surprising
And Flutter was initially based in React before adopting Dart, while Compose was Android's team response to the internal turf wars at Google.
It is to be expected that when forced to not use Android any longer due to politics, they would make a platform that eases the effort of developers with Android skills to transition to a new platform free of US politics.
Some might argue that the software has enough changes in it to be considered a distinct OS, but I'd rather just call it a hard fork as I had the impression that this was a more accurate depiction of what's really going on behind the scenes.