Has even a single Android phone received a major or minor kernel update ever (ex: 5.4 -> 5.10)? That felt like what Treble & creating an entirely Android specific way of building kernel modules (the GKI, "Generic Kernel Image", specifically for Android) was for.
Instead of having to upstream modules or support them against an ever-moving kernel interface, the kernel could move & drivers would have a special Android specific interface to code against that would be stable. That was the plan, yes?
But I'm not sure this has ever actually happened or gotten used yet? Android wrote it's own wrapper for the kernel, but is it even having the upside it was built for?
Android updates often do not come with kernel updates. Major kernel updates are difficult because of the tangle of proprietary modules in most Android kernels.
To partially answer GP's question:
Unofficial major kernel updates have happened in the past. OnePlus 6T, for example, shipped with 4.9.x, but supports mainline on pmOS.
Instead of having to upstream modules or support them against an ever-moving kernel interface, the kernel could move & drivers would have a special Android specific interface to code against that would be stable. That was the plan, yes?
But I'm not sure this has ever actually happened or gotten used yet? Android wrote it's own wrapper for the kernel, but is it even having the upside it was built for?
Recent thread on a 2021 post on Android kernel dev: https://news.ycombinator.com/item?id=37612699