I pretty much agree with this. For example, the BSD Handbook and documentation is the point of call for a newbie entering into the community and the codebase is much more readable than the Linux kernel.
Last time I checked, the kernel-newbies site doesn't seem to be beginner friendly and aside from following the IRC channel, the mailing list is still the way to do code reviews there, which is quite frankly pre-historic and very unfriendly for beginners sending patches at best.
At least for FreeBSD, they uses Phabricator for code reviews, HaikuOS uses Gerrit and SerenityOS uses GitHub and they seem to be the other OSes that have both good documentation about their kernels and their userland APIs. Perfect places to start learning about operating systems and kernels in general.
Last time I checked, the kernel-newbies site doesn't seem to be beginner friendly and aside from following the IRC channel, the mailing list is still the way to do code reviews there, which is quite frankly pre-historic and very unfriendly for beginners sending patches at best.
At least for FreeBSD, they uses Phabricator for code reviews, HaikuOS uses Gerrit and SerenityOS uses GitHub and they seem to be the other OSes that have both good documentation about their kernels and their userland APIs. Perfect places to start learning about operating systems and kernels in general.