Obviously most code in the NetBSD source tree is BSD licenced
Major exceptions are the default compiler - given the large number of platforms targeted by NetBSD gcc is still required, though both clang and pcc are in tree. Thats GPL, so still good on the FOSS front.
There is a port of Sun's ZFS which is cddl licenced.
NetBSD tries to keep externally maintained software neatly segregated under external/{licence_type} so you can tell cvsweb.netbsd.org/bsdweb.cgi/src/external/?only_with_tag=MAIN
There will be a few binary firmware blobs, but not that many