I haven’t kept up with this too much lately, but to my knowledge there is very little documentation or working code to set up a Darwin environment from scratch

I haven’t kept up with this too much lately, but to my knowledge there is very little documentation or working code to set up a Darwin environment from scratch with FOSS, and there aren’t any modern Darwin “distributions” because of this difficulty and lack of documentation and code. I wish this weren’t the case, but whatever PureDarwin has right now is probably about the closest you can get to a Darwin environment that boots without nonfree code.