Daring Fireball: Should Be Easy, Indeed:
The hard part is that what he’s really talking about is making his own phone with his own app store. (Android phones that don’t play by Google’s rules also don’t get access to Google Play Services, which is effectively a closed-source segment of the Android operating system. Outside of China, I’m aware of zero successful Android phones that don’t use the Google Play app store by default.)
This isn’t quite correct. You can create a fork of Android which can access apps from the Play Store, without the Play Store. There are open-source versions of the Play Store APIs, and you can use Aurora Store to access apps with or without a Google account. This is one of the ways Graphene OS uses optionally to run those apps.
But it is hit-and-miss. Like every kind of development which attempts to reverse engineer something, it will occasionally break and apps can go awry. It’s good, but not perfect – and I suspect that were a major figure like Musk to go down this route, Google would have legal teams on it in seconds.