Why don't we have an Android fork patched to fix all these "annoyances"? Android phone is just a computer, it should not be hard to unlock bootloader and flash it with anything.

I understand that it would be cumbersome on Apple devices with all their efforts to lock down the system, isn't Android different?

Manufacturers can prevent you from unlocking bootloader. Whether they are Apple or not. Samsung used to have a hard fuse that broke when you unlocked, it seems they now forbid it entirely.

Apps developers can decide to require Play Integrity so your Android fork cannot be used to run their apps.

Google can decide to not support or explicitly exclude your custom fork. Due to Play Integrity used on their own products, you cannot run Wallet on most forks where Google is not running as root.

Google can decide to delay or not publish source code so your Android fork cannot be maintained anymore.

Manufacturers, Google and developers can alter that deal at any point in time. Recently:

- Delayed patch of AOSP unless your are a partner: https://news.ycombinator.com/item?id=45158523

- Wall of shame of manufacturers locking bootloader: https://github.com/melontini/bootloader-unlock-wall-of-shame

Those "annoyances" are only one of the attacks made, and not all of them can be easily defended against without having the manpower to actually maintain your own hardware and software stack.

I think it's because the Android latest changes are designed to prevent it. In other words, you can complicate the system to bring it to the place beyond fixing of the annoyances, or fixing would remove features you've entangled into it.