OpenBSD on octeon (MIPS64) is supported on some network appliances. The Ubiquiti EdgeRouters are among these, and I found a mint EdgeRouter Lite very cheaply.
These devices have no video out. The console is serial, and the console port is an RJ45. So the first challenge is getting the console connected. Ubiquiti uses the same pinout as Cisco, etc. I tried my Sun console cable and discovered that it works. So step one was easy. Plug in a Sun console cable and set the bit rate to 115200.
Carefully reading the installation instructions from the OpenBSD website I removed the USB flash drive from inside the EdgeRouter and reflashed it with the OpenBSD installer. This is then replaced in the EdgeRouter and booted. The boot fails because U-Boot is still expecting the stock Linux setup. Some U-Boot commands to load the OpenBSD kernel and boot it come next. This gets the normal install process started.
Once the install is done the system is rebooted. Once again this fails, so those U-Boot commands must be reapplied and saved and the system reset. If you get all the commands correct it will now boot into OpenBSD.
The EdgeRouter Lite has two cores and 512MB RAM. It is quite slow to boot. Performance shoud be adequate in the network appliance role. It has a 12v 1amp power supply, so should sip the power. The unit does get warm to the touch.