Some public comments Linus has made about the choice to stick with GPLv2 over GPLv3: https://youtu.be/PaKIZ7gJlRU.
> and also most of the people using Linux right now are using it by accident, distributed as ChromeOS or Android
Also, those kernels are now built with LLVM. https://clangbuiltlinux.github.io/ (not all devices in existence, but all new ones for the past few releases of both distros and many old chromebooks that received recent kernel upgrades).