Back to OpenBSD... realize that it has no "unattended upgrades" capability. Until syspatch(8) appeared in 6.x you had to download patches and rebuild kernel and userland to get security fixes. Today, you could run syspatch(8) in a cron job but that only covers the base system. You'd need to handle any installed packages separately. And only the current and immediately previous release are supported at all. There are two releases a year, so you have to upgrade every ~6 months to stay in the support window.
Fortunately, with the introduction of the syspatch(8) and sysupgrade(8) utilities this is much simpler than it used to be. And, release numbers are just sequential with one point number, i.e. 7.0 was just the next release after 6.9, nothing more is implied by the "major" number ticking up.
Fortunately, with the introduction of the syspatch(8) and sysupgrade(8) utilities this is much simpler than it used to be. And, release numbers are just sequential with one point number, i.e. 7.0 was just the next release after 6.9, nothing more is implied by the "major" number ticking up.