So in my other comment I mentioned some specific(s) to (or rather, originated from) NetBSD, just as much as for example pledge() (fine-grained system call restriction), unveil() (filesystem visibility restriction), arc4random family[1] (ChaCha20-based CSPRNG), reallocarray() (integer overflow-safe realloc), OpenBGPD (BGP daemon), OpenOSPFD (OSPF daemon), httpd (web server), acme-client (Let's Encrypt client), signify (cryptographic signing tool), etc. are specific to OpenBSD.
DragonflyBSD has some goodies too while we are at it! For example varsym (Variable Symbol System - per-process environment-like variable substitution), nlookup (namecache-based path lookup replacing the vnode-based namei()), objcache (per-CPU object caching allocator), LWKT (Light Weight Kernel Threads - message-passing based threading), HAMMER2 (clustered COW filesystem with multi-master replication, successor to HAMMER), and so forth.
All popular BSDs have their own rich history. I know more about DragonflyBSD than NetBSD, so as an example: DragonflyBSD's core design philosophy centers on SMP scalability (cache-coherent token-based synchronization and LWKT message passing, avoiding fine-grained locking), OpenBSD's gist is security, and so forth.
[1] The ChaCha20-based CSPRNG (originally arc4random was RC4-based), which has been ported to other BSDs and some Linux systems.
(Sorry, I was really tempted to elaborate on these unique features and I felt like your comment was the perfect place for it!).
So in my other comment I mentioned some specific(s) to (or rather, originated from) NetBSD, just as much as for example pledge() (fine-grained system call restriction), unveil() (filesystem visibility restriction), arc4random family[1] (ChaCha20-based CSPRNG), reallocarray() (integer overflow-safe realloc), OpenBGPD (BGP daemon), OpenOSPFD (OSPF daemon), httpd (web server), acme-client (Let's Encrypt client), signify (cryptographic signing tool), etc. are specific to OpenBSD.
DragonflyBSD has some goodies too while we are at it! For example varsym (Variable Symbol System - per-process environment-like variable substitution), nlookup (namecache-based path lookup replacing the vnode-based namei()), objcache (per-CPU object caching allocator), LWKT (Light Weight Kernel Threads - message-passing based threading), HAMMER2 (clustered COW filesystem with multi-master replication, successor to HAMMER), and so forth.
All popular BSDs have their own rich history. I know more about DragonflyBSD than NetBSD, so as an example: DragonflyBSD's core design philosophy centers on SMP scalability (cache-coherent token-based synchronization and LWKT message passing, avoiding fine-grained locking), OpenBSD's gist is security, and so forth.
[1] The ChaCha20-based CSPRNG (originally arc4random was RC4-based), which has been ported to other BSDs and some Linux systems.
(Sorry, I was really tempted to elaborate on these unique features and I felt like your comment was the perfect place for it!).