Earlier quoted context omitted.
According to wikipedia, they moved to their own kernel in the 5.0 release last year: https://en.wikipedia.org/wiki/HarmonyOS_version_history
Okay so it won't run Android apps necessarily or be able to access the regular app stores/Play Store. It will need popular apps to be re-released for HarmonyOS NEXT
It does, they implemented a Linux-compatible API and ABI. They claim that apps run unmodified.