Nah, it turns out the switch is using an OS derived from their custom, proprietary 3DS OS.

They run the FreeBSD network stack in another process in user land, hence the copyright claim.

Still haven't seen anything showing this, including the license for the FreeBSD kernel can mean a lot of different things. Windows did/does ship with it, I wouldn't call it a fork.

If you mean the TCP/IP stack it was re-written from scratch on Vista.