Let me give you a simple example
AOSP is also known as the "Android Open Source Project". Since AOSP is open source, it can be used by anyone.
A pile of rice (Liunx-based AOSP),
Google takes it and steams it into rice (Android),
Xiaomi took rice to make millet rice bowl (MIUI),
Meizu took rice to make Meizu rice bowl (flyme)
Samsung made Samsung rice bowl (OneUI) with rice
Once Huawei took rice to make Huawei rice bowl (EMUI)
The reason why the UI is called UI instead of OS, just changed the next operation habits, adapt to user tastes, what Xiaomi Huawei Samsung, UI with comfortable and uncomfortable only their own experience can know.
Perhaps Huawei wants to steam out different rice (HarmonyOS), Hongmeng's future direction is indeed to do an operating system independent of Android, but unfortunately it is not at present, and it has not yet reached the disassociation from Android.
Once Microsoft Windows phone tried to be compatible with Android on the mobile phone side, and then it failed, and now Windows 11 comes with an Android virtual machine, whether it can also be considered that Microsoft wants to enter the mobile terminal is unknown.
Once Ali YUNOS just wrote a virtual machine to run with the Android virtual machine, and wanted to borrow the Android shell to stand on its own ecology, but it also failed.
If you say that compatibility with Android is to install apk, Google in order to limit third-party development, made a AAB format, although it is not yet popular, if there is another ojbk in the future, is it also possible to run?
Android actually mainly relies on AOSP to become the first choice for mobile terminals, code open source, ecological development, strong portability, including also inherited many features of Linux, Android is a derivative version of liunx, it relies on its own rich application ecology, defeated many of the nascent operating systems, became the first choice for mobile terminals, whether it is a self-service payment machine in the supermarket or a mobile phone, or a bank pos terminal, many have chosen Android.
The mac system can also be seen as a Unix case, but it is quite a good set. Hongmeng take your time. At the beginning, you will definitely use a lot of Android things, and if you can make a set of ecology and have your own characteristics and advantages, it will be very good.
HarmonyOS still has a long way to go to become a domestic operating system in the true sense.
In fact, for the operating system, if patriotic feelings aside, for ordinary consumers, there is no need to care about what he is, where the difference is, stable and smooth endurance signal, easy to use is the most important.