Yes, we provide extended support for end-of-life devices which had less than 5 years of proper support. We provide that for at least 1 year and no more than 2 years. However, unlike other alternate operating systems, we're completely honest about the insecurity and do not downplay it. We do not falsely claim to provide all open source patches and do not set an inaccurate Android security patch level. We try to strongly discourage using the extended support releases. We plan to add a notification about this to the OS which people can disable instead of only clearly marking it as insecure on the site.

We have extended support for end-of-life devices but discourage using it and make it clear that it's insecure. We dislike needing to provide it and many people don't realize we do because we make sure not to hype it up and instead try to get people to move to secure devices with full patches available. 6th gen Pixels moved to 5 year minimum support from launch and 8th gen moved to 7 years so we do not think extended support will make sense after the Pixel 5a. For now, we reluctantly provide it. There's a good chance we'll port the end-of-life Pixel 4a (5G) and Pixel 5 to Android 14 QPR2 to keep providing what we call "extended support" with all AOSP/GrapheneOS changes instead of "legacy extended support" with just backported patches. It's very unfortunate they didn't just extend the 4a (5G) and 5 to match the 5a lifetime despite it having the same SoC. It makes our life harder.

Android doesn't have a separate vendor security patch level. It has a single security patch level covering all of the Android security bulletin and OEM security bulletin patches. Most alternate operating systems set an inaccurate Android security patch level where they redefine it to mean AOSP patches. They added a separate Vendor security patch level to put the real patch level. The whole thing is strange because the whole point is having a simple overall patch level and being honest about it. The standard Android security patch level only includes Critical/High severity vulnerabilities now, not Moderate/Low severity, and it doesn't include a lot of things that are deemed optional or out-of-scope. Can see this by looking at the Pixel bulletins where there are tons of patches that are clearly generic AOSP patches for all devices and patches tied to components like the Exynos radio clearly used by other devices. Android Security Bulletin (ASB) and the patch level derived from it does cover a LOT of drivers/firmware, but far from all or even most.

The missing patches for end-of-life devices include a lot more than outdated firmware in practice since drivers stop being updated and maintenance doesn't get taken over by others. The kernel drivers are open source but it doesn't mean someone takes over maintaining them. It's often mistaken as having all patches to open source code and missing patches to proprietary code but that's not accurate since updating AOSP is not updating all open source code. Lots of device specific code including even large parts of firmware is open source. As an example, Pixels use Trusty OS for the TEE and secure core, littlekernel for the boot chain firmware, etc. Security patches to those open source projects are security patches requiring new signed firmware updates to be released despite being open source patches.