Google makes a special Linux version available for hardware manufacturers and Android. This version lets them easily add a bunch of proprietary hardware support to the kernel at the last possible minute. These modifications are not added to the mainline Linux kernel. This is the primary depreciation mechanism used to make phones disposable hardware. The stuff they are adding is the support for the processor architecture, hardware peripherals, and the modem. All of these elements are proprietary with no publicly available documentation. Every device is different. It would take years to reverse engineer each individual device using a 6 figure cost type lab.
Google makes a special Linux version available for hardware manufacturers and Android. This version lets them easily add a bunch of proprietary hardware support to the kernel at the last possible minute. These modifications are not added to the mainline Linux kernel. This is the primary depreciation mechanism used to make phones disposable hardware. The stuff they are adding is the support for the processor architecture, hardware peripherals, and the modem. All of these elements are proprietary with no publicly available documentation. Every device is different. It would take years to reverse engineer each individual device using a 6 figure cost type lab.