They can easily go back 30 years ago, when each one had their own proprietary in-house OS, using current Android as baseline, or something BSD like PlayStation.
They can easily go back 30 years ago, when each one had their own proprietary in-house OS, using current Android as baseline, or something BSD like PlayStation.
This is what phone manufacturers do. Very few use vanilla AOSP with just Google mobile services and their own hardware drivers.