There's probably a few hobbyists that still use SGIs. Octeon is mostly commercial vendors, who could pay for all of OpenBSDs needs out of their fancy executive toilet paper budget. And there's one OpenBSD hacker who uses Loongson, even GNU cult leaders use GNU/Linux on Loongson instead.

More than one OpenBSD hacker used loongson

If you want to support MIPS for embedded applications then loongson is one of the fastest and cheapest ways to run stuff right now.

How's availability outside of China? I'm not finding many of these systems in the US.

I don't know about the US but there is a place in the Netherlands that says they have netbooks and small systems in stock.

Good point, I didn't know MIPS is still used in the embedded space, I thought it was all ARM these days.

But OpenBSD could be testing on an embedded MIPS development device at any data center they want.

MIPS is on the rise again as recent SoCs are more power efficient than ARM. I don't have a source for this unfortunately.

Sony Bravia EX series televisions are MIPS and Linux based for example.

It's not power efficiency, it's money.

MIPS SoC licensing is less expensive than ARM licensing at the smaller volumes inherent in low-end routers (.vs phones and tablets).