The macOS Big Sur 11.0.1 kernel (XNU) source has been released here: source , tarball.
A lot of things have changed in Big Sur, and the installation and running of a custom kernel is significantly different from previous OS releases. This post covers building a kernel for x86_64 (Intel) platforms. It is not currently possible to build open source XNU for Apple Silicon Macs.Building XNU requires some patience, and some open source dependencies which are not pre-installed. This post walks through all the steps necessary to build the open source version of XNU and boot it on supported Apple Intel hardware.