Sure, see any of the previous exploits for sshd, or any other software shipped in the OpenBSD default install.
> I keep asking this as a long-time OpenBSD user who is genuinely interested in seeing it done, but so far everyone who has said "it's flawed" also reserved themselves the convenience of not having to prove their point in a practical sense.
The point is they have very little in the way of containing attackers and restricting what they can. Until pledge and unveil, almost all their focus in on eliminating bugs which hey, great, but let's have a little more in case you miss a bug and someone breaks in, eh?
An insecure dockerized webserver protected with SELinux is safer than Apache on a default OpenBSD install.