> You can't have a custom kernel if you can't rebuild the device tree.

What is this supposed to mean? There is no device tree to rebuild on x86 platforms yet you can have a custom kernel on x86 platforms. You sometimes need to use kernel forks there too to work with really weird hardware without upstream drivers, there's nothing different about Linux's driver model on x86. It's just that in the x86 world, for the vast, vast majority of situations, pre-built distro kernels built from upstream kernel releases has all the necessary drivers.