I've been buying these little boxes from AliExpress for years to use as firewalls and routers. My oldest one is almost 9 years old now! OpenBSD installs just fine. Just a BIOS tweak to always boot up after power is restored.
This posting is intended to function not only as a tutorial but, also, as a review and commentary on my ‘long-term’ use of spectrwm as my primary window manager (long-term, meaning at least one month of daily use).