Playstation is FreeBSD, yeah, but the Switch runs a completely bespoke microkernel. Nintendo did borrow the BSD networking stack, which led some to infer from the license disclosure that it runs a BSD, but it's been extensively reverse engineered now and it doesn't even vaguely resemble Unix.
The fun thing about it being a true microkernel is that although there's zero official public information about it, it was small enough to fully reverse engineer and more or less reconstitute the original source code. You can see it here, it's tiny: https://github.com/Atmosphere-NX/Atmosphere/tree/master/meso...
I’ve been trying to train a model to do this kind of work. Take a black box and try to reverse engineer its functions back into something usable (not necessarily identical). Obviously on things that are out of copyright or copyleft.
Interesting, I didn't know that! Thanks.