It's ironic that unofficial builds have been able to support these devices so much longer than their makers. LineageOS has done great things. And Amazon has shown that longer support is possible. The Kindle Fire HDX, released on September 25, 2013, and still somehow their best tablet, received its last security update on November 3, 2020.
Here’s the thing with unofficial Android upgrades: they don’t have complete coverage in their security updates.
LineageOS and Amazon can’t generally provide security updates for older chips. Only Qualcomm can compile new kernels for the Snapdragon 800, say. And Qualcomm stops giving you updates after four years (recent change: it used to be the three).
The updates LineageOS and Amazon and anyone else provides are updates to Android’s open source components. That’s all great - but they’re not complete security updates, and driver issues are a big vector.
This is true, and Qualcomm vulnerabilities have been some of the worst. This makes Google’s shift to custom silicon exciting if they’ll commit to long-term support. We should start thinking of the value of phones in terms of cost per supported year.
