Tbh..... imo I think it's the only BSD appropriate for this kinda project rn
OpenBSD is dominated by the dictatorship of that South African-Canadian chud, Theo de Raadt, who is almost singularly focused on "security" (a word which means many things to the OpenBSD project from good configurations defaults to uhhhh exploit mitigation techniques which have questionable utility at best). Their kernel is pretty much intended for them and only them and while they're changing shit out from under you if u complain about it on the mailing list Theo will probably call u an entitled [slur]. To be clear, I love OpenBSD, its my favorite Unix, and Google just ripped their libc for Android years back (Bionic) so its not unprecedented but I prolly wouldn't try to fork or base smth on their kernel unless I had development resources exceeding OpenBSD's team
FreeBSD is the Linux of the BSDs :3 (derogatory). Its codebase is massive, its code quality is sometimes worse than even Linux (see that incident a few yrs ago when some landlord wrote an in-kernel Wireguard implementation for them), and the development staff, at least to me >w<, seems overworked and too focused on features to implement things like basic exploit mitigation technology (it took them until fuckin 2021 to enable ASLR by default, not to mention that embarrassing incident some years ago when some security researcher started looking into the FreeBSD codebase and reporting serious security bugs that didn't even get a reply from the FreeBSD security team (to be fair, that was a long time ago))
I think prolly NetBSD is the only project that has ppl that might be open to working with an effort like this, has a codebase amenable to this kind of thing and which doesn't have part of itself ripped out every other year by ppl going over the code constantly with a chainsaw (OpenBSD) or have some userspace-breaking security change forced into it also every other year, and aren't too busy accepting commits from Netflix and Facebook to work on improving the codebase they already have
All of this is besides the project's positions on LLMs which I'm not very familiar with